Op-Ed: The Volt is an EREV, and Here’s Why


Perhaps the most debated feature of the Volt is its fourth mode of operation, which GM calls "Combined 2 Motor Driving"

Perhaps the most debated feature of the Volt is its fourth mode of operation, called “Extended Range Combined 2 Motor Driving”

Through all of the Volt-related stories on here, there is sometimes a vocal minority that declare the Volt is not an EREV. They claim they were lied to, cheated, and robbed of the promise of a pure series hybrid experience. They reference articles from third party websites that “prove” the Volt is merely a parallel hybrid, and they continue to criticize its design as a result of this mode.

Back to Basics: “EREV” Defined
First, let’s take a step back for all of our casual readers that may not be familiar with this terminology. The term “EREV” was invented by GM. It stands for “Extended Range Electric Vehicle” and was coined specifically for the Volt. The term describes a vehicle that is capable of some amount of electric range regardless of speed and acceleration – as long as the battery has charge remaining – without the use of any gasoline. Following depletion of the battery, a gas engine turns on to seamlessly provide additional power to take the vehicle as far as it needs to travel, as long as there is gasoline in the tank. Proponents of the technology love that they can perform their daily driving without using any gasoline, while also having the ability to take a long trip using gasoline, without needing to stop and recharge. The term EREV has more recently become synonymous with a “series hybrid” which I also describe below.

The best selling parallel hybrid on the market, the Toyota Prius, requires use of the engine for heat, fast acceleration, and high speeds.

The Toyota Prius, the best selling parallel hybrid on the market (without a plug), requires use of the engine for heat, fast acceleration, and high speeds.

“Parallel Hybrid”
Another term is “parallel hybrid” which describes the typical hybrid vehicles available on the market today. A parallel hybrid typically needs the engine at least some of the time to perform under various accelerations and speeds. The most common example of a parallel hybrid is the Toyota Prius. The electric motor operates “in parallel” with the engine, which is very efficient, but requires use of the engine the majority of the time. Under certain speeds and accelerations, the engine is not required, but when higher speeds or acceleration is needed, the vehicle can not provide these demands without use of the engine. Here, the electric motor is not the only source of kinetic power; the engine also directly provides kinetic power, much like traditional vehicles.

“Series Hybrid”
And the final term I want to touch on here is a “series hybrid,” which describes a hybrid vehicle that has its engine “in series” with the electric motor. Additionally, the engine is “behind” the motor, in that it only creates electricity, and the electric motor(s) are solely responsible for propelling the vehicle. Examples of series hybrids include the BMW i3 (with range extender option), as well as the Via Motors lineup of vehicles.

Which one is the Volt?
So the big point of contention is, where does the Volt fit in? Is it a parallel or series hybrid?

Well, the answer is really a little of both. For this reason, as I started out saying, GM coined the term “Extended Range Electric Vehicle” and since they defined it to describe the Volt, the Volt is by definition an EREV.

Will there soon be a similar debate over the additional fifth mode in the next-gen Volt's Voltec Propulsion System? "Stay tuned"

Will there soon be a similar debate over the additional fifth mode in the next-gen Volt’s Voltec Propulsion System? “Stay tuned”

However, first and foremost, the Volt is a series hybrid, and here’s why: When the battery has charge remaining, the Volt provides full power via its electric motors regardless of acceleration or speed. Floor the accelerator to 100mph, and the engine never turns on. Additionally, once the battery is depleted, the Volt always operates in series mode when under approximately 37mph. In this mode, one motor works in unison with the engine to create electricity, and the other electric motor uses this electricity to propel the vehicle. At speeds above 37mph – when maximum power is needed – the Volt still operates as a series hybrid. As such, the vehicle is mechanically capable of operating as a series hybrid at all speeds, and in fact does so whenever power demand at higher speeds is at its highest.

The engineers designing the Volt could have stopped there, but purely to increase fuel efficiency (think cylinder deactivation in a V8), they designed in a virtual parallel-like mode that some EV aficionados take exception to. While the Volt is 100% capable of being propelled in series mode at all speeds and accelerations, at speeds above 37mph and under reduced power loads, the Volt can indirectly link the engine to the wheels through one of the electric motors. By doing so, some inefficiencies of conversion are eliminated. Rather than converting the mechanical energy of the engine to electricity, then converting the electrical energy back to mechanical energy to propel the car, the engineers provide this indirect mechanical link to the wheels: the engine is coupled to one of the electric motors (which normally acts as a generator), and that electric motor instead turns the drive shaft. Doing this provides the same “electric” feel, but results in a 10-15% efficiency improvement under these load conditions, by avoiding the conversion losses from mechanical to electrical energy and back. Again, thinking back to a V8 with cylinder deactivation, nobody would ever claim such a vehicle is anything other than a V8 despite 4 cylinders being deactivated at higher speeds and lower power demands to save fuel. In the same way, the Volt is first a serial hybrid; it doesn’t perform this virtual “parallel” operation because it needs to, only because it saves fuel… and if you demand more power by flooring the accelerator, it resorts back to series operation, just like that V8 would reactivate its remaining 4 cylinders under the same scenario. The video below is one of the best I’ve seen describing the various modes of operation that comprise the Voltec drive train, which is a great animation of the modes I’ve tried to summarize.

Now for some unexplained reason, there are a few EV advocates that take great exception to this additional mode that is purely there to increase efficiency and minimize gasoline use. Somewhat ironically, they would apparently rather the Volt operate as a pure series hybrid all the time and burn more gasoline, rather than providing the same electric drive and smooth torque with greater efficiency at higher speeds and lower engine power requirements. This continues to baffle me and many others, who recognize the potential the Volt has to eliminate daily gasoline use while also maximizing efficiency for longer trips at higher constant speeds.

Some hate the Volt because Obama likes it.  Others hate the Volt because of the bailout, and still others hate it because of this virtual parallel mode.  Can't we all instead like the vehicle for the promise it holds?

Some hate the Volt because Obama likes it. Others hate the Volt because of the bailout, and still others hate it because its not “always” a serial hybrid. Can’t we all instead like the vehicle for what it is? Clearly owners love the car, and they should know best right?

The fact that the Volt is 100% capable of providing full acceleration and top speed using only its electric motors makes it just like an electric vehicle for the first 40 or so miles. (See Footnote 1 below) This is untrue of many other plug-in hybrids such as the C-Max Energi, Fusion Energi, and Plug-in Prius. Unlike the Volt, they will require the use of the gas engine to avoid sacrificing acceleration and/or to reach top speed.

Additionally, the Volt is 100% capable of providing full acceleration in series mode once the battery is depleted, with very few exceptions. The Volt doesn’t stop there though, and implements a virtual “parallel” mode at higher speeds and lower power demands… not because it NEEDS to do so, but because it saves even more gasoline without sacrificing performance. The only other main competitor to the Volt, the BMW i3 with range extender, does not have the same capability to provide the same performance under extended range operation. The engine is simply not sized for the majority of conditions, and the “pure series” configuration further prevents some efficiency gains under higher speeds.

In Summary…
As a result, the Volt (and its sister, the Cadillac ELR) are really the only two nationally available and commercially viable “Extended Range Electric Vehicles” on the market today. They provide meaningful all-electric range, and no sacrifice in performance once the battery has been depleted and the gasoline engine kicks in let you travel as far as you desire. No other mainstream vehicles on the market can make this aggregate claim, and that’s what makes the Voltec technology so promising. (As noted above, the BMW i3 with range extender comes close, but its engine is too undersized to provide the same performance over the majority of driving situations once the battery is drained). The Voltec technology is the “gateway drug” that will allow mainstream consumers to fall in love with pure electric drive, and eventually purchase full electric vehicles once ranges are sufficient and fast charging is prolific. This capability has led to over 72% of Volt miles being traveled purely on electricity alone without a drop of gasoline, and an average of over 120 miles traveled for every gallon of gasoline used (source: VoltStats.net).

After The First Gen Chevy Volt Accidently Broke Cover On The Set Of The Transformers, GM Hopes To Make It All The Way To The NAIAS With Gen 2

The Volt was the most loved car by vehicle owners two years in a row, and continues to be the most loved car in its segment.

TL;DR for the Mass Market Consumers
For the average consumer that doesn’t care to learn the terminology, simply know that the Volt is arguably the only affordable solution to a pure electric vehicle with sufficient gas-free range for the majority of American commuters and their daily driving, with the ability to continue driving beyond that range with no stopping or performance degradation as long as you have gasoline in the tank.

So to the few vocal EV advocates, let’s stop criticizing the Volt’s virtual “parallel” mode like it is as an Achilles heal. It provides greater efficiency with the same electric feel, winning more awards (and some more listed here) in the last 5 years than I can count. Instead, take the time to understand the technology, and educate potential consumers on the potential it holds: gas free daily driving, and the ability to take a 1,000 mile road trip without a second thought. There’s a reason why the Volt continues to be one of the most loved vehicles, and as such, the Volt is one of the best “gateway” technologies to help mainstream consumers begin to transition to purchasing full electric vehicles.

Footnote 1: In sub-freezing temperatures, the Volt will occasionally cycle its engine on and off to provide added cabin heat when the battery still has remaining charge. This requirement is apparently an artifact of outdated rules requiring engine use to help defrost the cabin more quickly. The Volt is still capable of heating the cabin without the engine using its resistive heater, but the regulations for defrosting have required engine use despite it not being strictly necessary for typical operation. Even so, this still results in much less gasoline use than other plug in hybrids like the Plug in Prius, which require the engine to be running whenever heat is requested, regardless of outside temperature.

Footnote 2: The author of this story has no affiliation with GM, professional or otherwise. He has no relatives, friends, or acquaintances that work at GM. Additionally, he does not have any financial investments in GM. He does own a Volt though, and it is hands-down the best vehicle he has ever owned. As a result of the Volt, the author will never go back to a vehicle that doesn’t have a plug.

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214 Comments on "Op-Ed: The Volt is an EREV, and Here’s Why"

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Well, that’s your opinion…


Sorry, Mr. Cote, I just could not resist.

I disagree with labeling this an Op-Ed. It is more than an opinion, the Volt is an EREV by definition. GM coined the term just to describe the car. Thank you, Eric, for laying this out.

It’s sad to me that there is so much in-fighting within the plug-in enthusiasts. We all have the same goal – to transition transportation from gasoline to electricity. The Volt is one of the best options available to do that. And it is THE best for the largest number of people.

I applaud your tenacity to comment first knowing when the article was going to go live, without ever reading it, all for the sake of humor. 😉


Thank you Mr. Cote. I know it seems repetitive and tiresome to educate, but this article is a gold mine

For 2 years I was dead set on BEV only. Then when I saw the range issues of BEVs excluding Tesla in MN winter I realized a REx or EREV was necessary.

But I was saddened on the Volt’s AER and the fact that it burned gas

But due to people like you (and GM which redesigned the Volt) I now feel comfortable with it at least until better BEVs are feasible in 2017 and beyond

So shockingly to me it appears that a volt will be my next car!


Love the new design, 50 miles EV range and interior of Volt. Anxiously awaiting the arrival of #Model3 by Tesla in 2017-2018. In the meantime the Volt is the perfect transition car. Over 90% of my driving will be on cheap local electricity!


Are you sure GM invented the term “Extended Range Electric Vehicle”?

I seem to recall Chrysler announcing a range extended electric minivan in 2008 or so, but then they went bankrupt and the plan fell away.

MTN Ranger

The Chrysler T&C PHEV was talked about 21 months after the Volt Concept was introduced. So, quite a bit later.

Brian Smith

I’m a bit of an EV snob, and I have never understood why anyone would get so worked up about what parts of the car are working when. I’m happy to know that the car is doing whatever is most efficient at that moment, period. My job as an EV nerd is to try keep it electric as long as I can.

Don’t let the perfect be the enemy of the good. Whatever its doing, the Volt is much more efficient than most cars out there; if it acts as a stepping stone for nervous customers to get used to EVs, so be it.

“Don’t let the perfect be the enemy of the good.”

One of my most favorite phrases, and something to always remember. 🙂

David Murray

I have never understood the purists who complain about the Volt not being a true series hybrid. I’ve often asked what the advantage would be of such a setup and have yet to hear a compelling answer. Obviously GM made the right choice.

The way I see it, once you are out of battery power, you are going to be burning gasoline. And since you’re already burning gasoline at that point, it might as well be as efficient as possible.

I also consider the i3 Rex to be an EREV. After all, it is an electric vehicle with a range extender. How could anyone argue with that?


One has a BMW logo and one has a GM logo. So they are completely different.


Yes, one has a Bavarian flag, while the other wears a bow tie. But that is not why they are completely different.

The Volt is designed to be your only car. It can just as easily drive coast-to-coast as it can drive your daily commute. It just does the latter without burning gasoline.

The i3 is designed to be a megacity car. It can do your commute, and then some. It has a small generator so that you don’t accidentally get stranded, but that’s about it. It CAN go on longer trips, but that is not what is was built for.


For those who mistakenly believe (like I once did) that the BMW emblem was a reference to the Luftwaffe, it’s not a white propeller on a blue sky. It is a symbolic representation of the Bavarian flag.



If you didn’t know that, you haven’t been to Oktober Fest enough


Oktoberfest near me is an insult to the German people…

And yes, I was familiar with the Bavarian flag. Heck, my family immigrated from Bavaria. But I was always told that it was a white propeller on a blue sky, and never had a reason to question that.

Calitran Dresdener
The logo IS representative of a spinning propeller. AND it is done in the colors of the Bavarian flag. But it is not the Bavarian flag. The flag is composed of many blue and white diamonds usually with a shield or a crest centrally superimposed on it. Sraight from BMW is this origin history… “1916 – Establishment of BMW. BMW can trace its roots back to Karl Rapp and Gustav Otto. In 1916, the Flugmaschinenfabrik Gustav Otto company had merged into Bayerische Flugzeug-Werke AG (BFW) at government behest. Elsewhere, in 1917, the Rapp Motorenwerke company morphed into Bayerische Motoren Werke GmbH, which was duly converted into an AG (public limited company) in 1918. BMW AG subsequently transferred its engine construction operations – including the company and brand names – to BFW in 1922. The date of BFW’s founding, 6 March 1916, has therefore gone down in history as the birth-date of Bayerische Motoren Werke AG.” A flugzeug is German for an airplane. This is what the company first made. In 1923 they started making motorcycles, then in 1928, their first car. Yes, it can be argued that BMW choose later in the 20s for the BMW logo Roundel to represent… Read more »

“So beware, not all information found on the web is true. You can even be skeptical of this posting.”

I don’t believe it! LOL!

Thanks for the history lesson. I’m generally skeptical of anything I read, particularly on the internet. Somethings are worth digging into and others (like a company’s logo) linger in my mind without any motivation to follow up. In the end, there is rarely universal agreement on any “fact”. Such as whether the Volt is an EREV, for example 😉

Calitran Dresdener

1917 – The BMW Emblem.

“From 1917, each of the company’s products proudly displays the BMW emblem, which incorporates the state colours of Bavaria. At the end of the 1920s, the emblem makes its first appearance in the company’s advertising as a rotating propeller – taking a form that will be used as the logo long into the future.”

From BMW’s own history web page.


Leaf owner here. An excellent review and summary. Thanks. Finally, someone who helped explain this to me (I’ve given up trying to read the arguments back and forth in the comment sections). I always try to educate people to choose the product that helps them get the most EV miles for their use pattern.


While it may be opinion, in fact the conclusions are straightforward and accurate.

Some people take exception to the Volt because they are religious wing nuts. They think that if a vehicle has an engine then it’s an abomination. Better to have two cars, one fully powered by a motor and one fully powered and engine, than to have one vehicle powered by both. No doubt they fly virtuous even when flying lots of places and renting an SUV for longer trips. LOL

Then there are the people who don’t like GM for whatever reason and want to demean the technological achievement by claiming the Volt is “just like the Prius”, which of course it’s not.

Not sure there is hope for members of either of these groups.

This should be classified educational, not opinion. A great overview of the facts of how the Volt works. You even went through to point out where the point of contention exists.

I never try to explain this level of detail to others when a recommend a Volt to them. I just say “you can do your daily commute on electricity and drive on gas when you go on a longer trip.” Even though I haven’t owned a Volt myself, it is the vehicle I most often recommend to plug-in novices.


thanks for the info. really interesting.


Why is it so important to split hairs? Articles like his inspire disagreement. It’s as if the Volt community wants to somehow deny the Volt uses gas.


I somewhat agree about splitting hairs, but what part of defending the Volt as an EREV denies that it uses gas?


Why is it so important how many different ways you can combine gas and electric. There are debates if the CMax is an EREV or not. Who cares. Hybrids by definition have gas and electric. There are many many ways you could combine them and have them interact. Is it really necessary to make up a new name for every nuance.
GM was trying to get the best of both worlds. Try to claim it’s pure electric, but uses gas, so they invented a new term. That’s why it’s so important to call it an EREV instead of (heaven forbid) a hybrid.

The vast majority of Volt owners care about using all electric whenever possible the same as a BEV driver. In many cases, they choose one EREV opposed to a BEV and an ICE. That is the difference.

Calitran Dresdener

I’d suggest that it is an important distinction because of the quality of the driving experience. You are essentially always driving off an electric motor and therfore no shifting gears or engine response delays. This assist from the engine coupling in a 1-1 ratio of the motor to benefit from the increased efficiency it provides does not alter the electric driving dynamic. And as such, even if it is only a GM designation, the car is an EREV series hybrid, assisted directly by the engine when it is optimal to do so.


Here is why many take concern that the Volt is not a pure serial hybrid. The answer stands in a short response, the remaining connection to the wheels force the generator to be a crank and shaft outdated generator. There is simply no other possibility to have a rotational transmission with high torque change capability. That is a problem because it means the Volt therefore can never get access to the superior generators like a free piston direct generator and even less a direct bioethanol fuel cell. You get just sticked into that damned permanent crank and shaft model and all its associated complexity, weight, oversize, friction loses, oil requirement, cost and high maintenance. The only way to get rid of that is PURE serial hybrid.

Jeff N

As the article stated, the Volt is capable of operating in series mode at any torque demand or vehicle speed. If GM wanted to substitute an alternative generator technology in place of the gas engine but keep the existing transmission hardware they could trivially modify the control software to operate the car as a “pure” series mode vehicle after the battery was empty.


Aside from a free oil change after 2 years, I’ve had no maintenance needed on the engine in my Volt.


“The only way to get rid of that is PURE serial hybrid.”

But PURE series hybrid can NEVER be as efficient as Parallel hybrid at constant speed with constant load.

That is why Volt varies from parallel to series depending on which mode is most efficient.

That capability makes Volt unique.


“That is a problem because it means the Volt therefore can never get access to the superior generators like a free piston direct generator and even less a direct bioethanol fuel cell. You get just sticked into that damned permanent crank and shaft model and all its associated complexity, weight, oversize, friction loses, oil requirement, cost and high maintenance. The only way to get rid of that is PURE serial hybrid.”

I guess you posted here without reading the article first.

No wonder you call yourself Priusmaniac… You just don’t know better…


For sure the Prius is now outdated but I wouldn’t call the Volt crank and shaft generator a modern marvel but rather a steam engine in an iphone. The direct Free Piston generator is simply better on all counts. It even give a better yield converting gasoline to electricity and then using that electricity in a motor then the so called direct transmission in a standard engine because you don’t lose all the frictions that take place in the crank and shaft conversion, the lateral push on the cylinder heads, the oil viscosity losses, the clutch friction losses, the gear box losses and the gear box oil viscosity losses. GM is just not even giving it a try, or they have given it a try and know it would be the end of all their standard engines cars and they just don’t want that out of conservatism.


Wasn’t this discussed to exhaustion in 2011?


Yes, yes it was.


Apparently not enough exhaustion. Many still claim that the Volt is “a hybrid just like the Prius” and “not an EV”. At this point they do it out of malice rather than ignorance. Eric did a good job for those willing to read and understand, but I am afraid many remain that are not.

As a Volt owner however it is indeed exhausting arguing with people on both side of the fence what the Volt is and isn’t. The latest argument stemming from this is since the Volt is “not an EV” it should not be allowed to charge at public stations… The nerve some people have is really something.

I think you hit the nail squarely on the head. The answer to why people don’t like the labels assigned to their cars is because of the association. The statement “You drive a volt, that’s a hybrid like a Prius isn’t it?” is very provocative to most volt drivers just like the statement “You drive a leaf, that’s an electric car like the volt isn’t it?” irritates Leaf drivers. It’s nothing to do with the technology and everything to do with which box you find your self in, which is why no matter how many excellent technical articles are written people will still be irritated about how you refer to their car. Just to prove my point, other statements that people will be offended by: “I’ve had my massive SUV converted to run on hydrogen, it’s zero emission” “I’ve had my car converted to run on pure ethanol it’s zero emission” “I’ve just bought an i8 its an electric car” “A Toyota Mira is a fuel cell electric vehicle” or even more frustrating for some in the blog-o-sphere “A Toyota Mira is an electric car” “The Nissan Leaf and Tesla model S are both equipped for fast charging” The list… Read more »

I don’t know if your joking, but I don’t understand why any of those statements would be considered offensive. Maybe some people are simply too sensitive.


I have certainly seen people being quick to correct people on the “electric car” statements. There are plenty who would tell you that anything with an engine is a hybrid and that electric cars do not have engines or that fuel cell vehicles are not electric cars.

I still think most arguments around definitions or classification of technologies are caused by people liking to cling to the “brand” surrounding their car with the drive train being very much a part of that “brand”. Even in the ICE world turbo’s, V8’s and rotatory engines all mean something to some folk – they probably couldn’t tell you what the difference between each technology is but they will pay extra for a V8 or hybrid depending on what type of person they are.


The Volt is especially hard to accept because it doesn’t fit in any of these buckets. It transcends categories, confuses people, makes others angry, and third use it as a political punch ball. It is full of contradictions yet it holds a simple truth.

Is it electric (el. motor propulsion)? Yes.
Is it a battery car? Yes.
Is it a plugin? Yes.
Is it range-extended? Yes.
Is it a gas car? Yes.
Is it a parallel hybrid? Yes.
Is it a serial hybrid? Yes.
Is it a normal car (range, controls, features)? Yes.
Is it a GM car? Yes.
Didn’t GM kill the electric car? Yes.
Didn’t GM go bankrupt? Yes.
Didn’t the gov’t/Obama(D) save GM and the Volt? Yes.
Didn’t Bob Lutz(R) create the Volt? Yes.
Didn’t Bush(R) sign on the EV tax credit? Yes.
Didn’t he also slammed the door on EVs by unleashing the hydrogen shell game? Yes.
Aren’t some 70,000 odd people driving a Volt now for over 4 year without the world coming to an end? Yes.

And when the most important question finally comes:

Should I just accept it and get one?

they get stumped. They can’t say a simple Yes.


Thanks for this comment. I think your characterization of the situation is very accurate.

Bill Howland
Yeah, brings up a lot of silly arguments. As an example last fall I drove my Roadster to a tech training center for a complementary demonstration. A big Electrical Engineer ( I know this because he told me this several times ) told me the best way to charge my Roadster was at the slowest rate available, to which I mentioned that would be 12 amps 115 or thereabouts (he was non conversant with the car, as will be proved). I mentioned that this was not the best way to charge the car since most of the electricity would end up as heat. He said that since P = I squared R (it does, but its rather like saying if you live in a flood plane and the drinking water is expensive then you never have to worry about floods since the water is too expensive. Which is of course irrelevant, but it is here too), the lowest loss will happen at the slowest charge. I mentioned there are other losses besides the internal resistance of the batteries, that there are other rectifier losses that old time battery chargers didn’t have. He said that’s nonsense since you only need one… Read more »

Shockingly (pun intended?) I’ve also been told that this large amount of overhead in Tesla vehicles (at least the Roadster) makes 16 amp 120V charging twice as gas as 12 amp 120V charging. Which, by extension, also means the Roadster could never charge at 8 amps like the Volt, since that first kW all goes to charging overhead.

So inefficient.

Twice as fast, not twice as gas. Sigh.

Bill Howland

Unfortunately, although a #12 awg cord is supplied with the Roadster (that yellow thing I had plugged in at MOMA), the choices are only 12 or 15 amps. 15 amps at 120 is also pretty lousy. Foreign versions get the same cord with 16 amps @ 240 which is a fairly decent charge rate (in the roadster only this is only somewhat less efficient than the most efficient rates, which are 7 1/5 to 9 1/2 kw). Other tesla chargers in other vehicles, S, rav4ev, mercerdes b-class, and I don’t know about the old smarts cuz the new smarts use mercedes own charger, but anyway other tesla chargers are equally efficient at all 240 volt rates, which is *NOT* the case with the Roadster as mentioned.

If I didn’t have an EVSE I would have tried putting 240 on the cord and look to see what happened. I was told that foreign roadsters have different downloads, so maybe I could have requested a british software download to get the 16 amp 240 volt feature. I asked tesla at the time and they said they didn’t think it would work for the american download.

Bill Howland

The other issue is that there are 2 completely different chargers in the Tesla Roadster, the one they’ve always used, and the very heavy Transformer type (new) they use in the 2.5 and Sport.

Before this they used the stationary drive motor for the step up voltage, and they didn’t have to worry about generating any torque since Roadsters can only take (even in the foreign versions) single phase power, and with single phase excitation there can be no rotating magnetic field therefore the drive motor *Cannot* turn. Why they decided to change this for only the latest model I have no idea, unless there was a litigious issue with American Propulsion’s so called ‘reductive charging’, and Tesla made a compromise by putting a heavy transformer in the P.E.M. to quiet AP down.


It seems to be primarily the BEV purists that insist that any vehicle capable of using petroleum for fuel is essentially the same as driving a Hummer H2; all are equally culpable for destroying the planet.

There’s a reason why the Volt has logged more electric miles than any BEV. As a Volt driver, I have no problems whatsoever using up every single mile of EV range any time I get in the car. If I were a BEV driver, such a prospect would be terrifying.

Jeff N

The overall content of this article is good but it does confuse things a bit by referring to EREV and then discussing series vs parallel gas engine operation.

The term EREV was popularized by GM. Their proposed definition is documented in a 2008 SAE technical paper which is available here:


If you read it carefully, their definition does not specify what happens after the gas engine starts up. Rather, it’s all about the propulsion behavior of the car when the battery has usable charge remaining in it.

It sets the following requirements under its Main Section on page 4 of the document (page 6 according to a PDF reader app):

1. The range extender (gas engine) will not start due to torque demand (accelerator pedal position)

2. The range extender will not start due to vehicle speed.

3. The car must be capable of full power driving on the highway, as defined by a document published by the California Air Resources Board. In other words, the car is not a low-speed neighborhood electric vehicle (golf cart).


GM also coined the phrase “range anxiety”.


Actually it was coined by pioneers during Westward Expansion. Lot’s of danger out on the range 😉


“The term EREV was popularized by GM. Their proposed definition is documented in a 2008 SAE technical paper which is available here:”

Popularized? Nope.

Who knows what it means outside of a few car blogs? Nobody.

If GM uses “EREV” in their marketing, it will fail again just like it did last time. I would drop that term and market it with blurbs like this…

The new Chevy Volt is a 50 mile electric vehicle and a 350 mile hybrid.
Volt is where silent electric performance meets efficient unlimited range.
Volt still has no equal even after five years, and now it’s even better.
Test drive one at your local Chevy dealer.


Agreed. Fixating on defining a new term, EREV, makes it seem to the public that they’re trying to hide something. It’s a electric gas hybrid that is able to run in pure electric until it runs out of charge, no need to over complicate.


Agreed. Fixating on defining a new term, EREV, makes it seem to the public that they’re trying to hide something. It’s a electric gas hybrid that is able to run in pure electric until it runs out of charge, no need to over complicate.

So glad “EREV” was coined. How else were we going to pick on all the tiny battery PHEVs that have shown up since?

There’s a difference between fully functioning electric drive, with range and POWER, and what may as well be “enhanced stop / start” engines.


Agreed, but conveying that difference does not require new confusing acronyms like PHEV and EREV. Such acronyms have proven to be a marketing failure. Instead, they should leverage simple terms that people already know. For example:

Introducing the all new Chevrolet Volt.
It’s a 50 mile plugin-electric vehicle and a 350 mile hybrid in one.
Volt is where instant silent acceleration meets efficient unlimited range.
Volt still has no equal even after five years, and now it’s even better.
Test drive one at your local Chevy dealer.


I like it. I’m sold.


GM did try to hide something. They didn’t announce that the Volt would function as a parallel hybrid some of the time until people figured it out.

Jeff N

GM revealed the parallel capability to media outlets like MotorTrend in October, 2010 about 2 months before the first Volt’s were delivered to customers.



It wasn’t only GM who thought this was a good idea.

“As was alluded to in the customer town hall meeting last week, Tesla will likely provide both pure electric and range extended electric drive options in the future. We refer to the latter as a REEV (Range Extended Electric Vehicle) to distinguish it from “hybrids,” which are really just gasoline engine cars with a small electric motor and tiny battery. The REEV battery in our scenario would fully cover the range needs for reasonable daily usage, but there would be an onboard generator for the occasional long trip.”
— Elon Musk, December 21, 2007


Calitran Dresdener

The new Chevy Volt is a 50 mile electric vehicle and a 350 mile hybrid.
Volt is where silent electric performance meets efficient unlimited range.
Volt still has no equal even after five years, and now it’s even better.
Test drive one at your local Chevy dealer.

Open Mind, this is an excellent set of marketing phrases. Excellent.

I wonder if Lustuccc will read/understand this…



Jeff N

Under GM’s definition, the Volt and the Cadillac ELR are EREVs.

The BMW i3 would be an EREV as well.

Even the Ford Energi plugin models might be considered to support EREV operation since the will not start the gas engine due to torque demand or vehicle speed when placed in EVNow mode (which is persistent across restarts). In EVNow mode, the Energi models have the 0-60 and 1/4 mile track performance of a 4-cylinder Ford Pinto which CARB would consider to be at least minimally capable of highway driving.


At least the gen2 Volt no longer requires premium petro to run. So, kudos to GM for that brilliant update.

Still gonna count the number of recalls issued to it…


Premium has some advantages, but the Volt doesn’t really “need” it:



“Still gonna count the number of recalls issued to it…”

At my last count, the number of general recalls on the 2011-2015 Chevrolet Volt stand at zero:


Count again.

8000 Volts Recalled to modify the battery packs to prevent fires from coolant leaks, plus structural reinforcement:


Another involved 4 vehicles having a Stability Control Glitch:


Actually, the 8000 vehicles was not a recall, though people tend to misuse the term. The action on GMs part was voluntary, called a service campaign. The “crash test” that it was in response to was largely mischaracterized and surrounded by politics, with this service campaign being unnecessary in my opinion.

You are correct about the 4 vehicles. 4 out of tens of thousands rounds to zero in my mind though. 😉


Anon just finds every possible way to hate on GM and therefore the Volt…


Eric is right, Anon/Volt hater is wrong. Nothing new.

John Hansen

Re-read the article you linked to. It wasn’t mandated so it isn’t a recall. So you entire point stands on four, as in 1, 2, 3, 4, Volts being recalled. Lame.


The Volt is a PTEREVPTHEV.

Part-time electric range-extended vehicle, part-time hybrid electric vehicle.


Jeff N

The article’s description of the Volt’s “virtual parallel-like mode” is a little misleading. This mode is very similar, but not identical, to the parallel-like mode in the Prius.

In both the Volt (when some clutches engage) and Prius, the gas engine has an indirect mechanical linkage to the wheels with the power flow being modulated through a planetary gear set by an electric motor. The Volt parallel arrangement is not any more “virtual” than the Prius arrangement.

In the Volt, the gas engine and small generator motor are on the ring gear, the big motor is on the Sun gear, and the wheels are connected via the planetary carrier.

In the Prius, the gas engine is on the planetary carrier, the small generator motor is on the Sun gear, and then wheels and the big motor are on the ring gear.

Technically, the Volt is an output-split arrangement and the Prius is an input-split arrangement but both are considered to be power-split designs. They have different tradeoffs but for the most part they provide a similar level of indirectness between the gas engine and the wheels.


The input split allows Prius to be powered by Gasoline engine alone.

The Volt can’t be powered by engine alone.

Jeff N

Not true. Neither the Prius or the Volt can be operated entirely by the gas engine alone.

In both cars, the gas engine is attached to 1 of 3 gears on a planetary gear set. In both cars, the gas engine and the wheels are hooked up to different planetary gears. In both cars, there has to be resistance or “resistance torque” on the third gear in order for the gear hooked up to the gas engine to pass mechanical power to the gear hooked up to the wheels. In both cars, that third gear (the Sun gear) has an electric motor hooked up to it. That electric motor on the Sun gear has to resist turning rather than spinning freely in order for the mechanical power to flow from the gas engine on one gear to the wheels on the other gear.

There are other differences in how the Volt and Prius transmissions are arranged but that 3 gear arrangement and need for the electric motor to actively participate when the gas engine is running is something the cars have in common.

This seems semantic though, which is why I tried to focus the write up on the results of each design, rather than their inner workings.

But to your point (I think), both vehicles have some great engineering design in them, and they serve their individual purposes quite well.

The Prius was never designed to be driven solely on electricity, and was instead designed to sip fuel. And it does that very well.

The Volt was designed to be gas free for 25-50 miles, with a pretty efficient gas engine hybrid configuration after, and it too does very well to accomplish its intended purpose.


Still don’t see the purpose in nit picking the difference. Encourages disagreement.

Other hybrids that sound like EREVs include the BMW i3, Ford C-Max and fusion energi, Toyota plug in Prius. Basically any PHEV or plugin hybrid.

Jeff N
No. The Prius Plugin fails all 3 requirements under GM’s EREV definition: 1. The Prius Plugin starts the gas engine if you press the accelerator too much when there is usable battery charge remaining. This is why the EPA gives it an All Electric Range of 6 miles even though it rates the battery range as 11 miles with a small amount of gasoline used. The EPA test causes a little too much acceleration 6 miles into the test and it causes the gas engine to start. An EREV must not start the engine due to accelerator position (torque demand). 2. The Prius Plugin starts the gas engine if the vehicle goes above 62 mph even though the car’s top speed is a little over 100 mph. An EREV must not start the engine due to vehicle speed. 3. The Prius Plugin might not be considered to be a full-powered electric highway vehicle according to a California Air Resources Board definition because of its speed limitation and weak acceleration at highway speeds under only electric power. An EREV must meet the CARB definition. Certainly, a BMW i3 with range extender meets these EREV requirements. A Ford Energi would also meet… Read more »

Actually, the power can be transmitted from planet carrier to the ring gear if the axis of the planet gears don’t spin even if the sun gear spins freely…

So, the planet gears would lock to sun gear in this case and all the power will transmit directly to the ring gear.

The difference is that if Volt does this, the ICE will NOT meet the torque requirement of the car where the Prius can due to the increased gearing ratio.

So, you are right, technically they either both need electric motor or they can brake the planet axis to allow single powertrain driving. But in the Volt case, that is NOT practical but in Prius’s case, it is perfectly okay and it will even generate power thru the sun gear based generator.

Jeff N

How exactly do they “brake the planet axis” while the Sun gear spins freely so that gas engine power can flow to the wheels. Neither the Volt or the Prius have a clutch brake on the Sun gear.

If the wheels are on the road they will have much more reactive torque than the Sun gear so all mechanical power will flow to the Sun and the car won’t go anywhere much like a conventional differential will direct all rotation to a wheel that is not in contact with the road.


It’s difficult to explain in words, but the interactive Prius Power-Split-Device simulator on the following webpage illustrates what ModernMarvelFan is saying. Just drag the sliders for MG2 and ICE to see how power is combined. Enjoy!



You don’t have to brake the sun gear, you only need to prevent the planet gears from spinning. But the planet carriers can rotate with the sun gear without spinning each planet gears. That way, the planet gears effectively becomes “fixed extension” to sun gear. That fixed extension basically powers the ring gear.


Nice. Didn’t even use the word “clutch”, and there are five that allow things like the decoupling to run discreet series mode.

I think “clutch” is in Tesla’s future. If not for the sake of greater efficiency through decoupling AWD, than for a new level of brutal acceleration in its top end.

Volt 2 is different than Volt 1, and I’m curious how we’d depict that? My understanding is that where Volt 1 had two rotating electric motors, one turned more slowly than the other. Volt 2 has two motors, at the same spin ratio to the drive line. Correct?

I ask because I’m wondering what’s going to happen at that moment we most feel the switch off from one motor, to the higher speed one, on highways. That delay. Will there only be one speed at which we accelerate from a steady ~65mph, with Volt 2? Will it be better/worse, in electric mode? Will both motors engage more instantaneously? Thanks, if anyone takes a stab.


Tesla already tried to develop a transmission for, as you so aptly put it, “brutal acceleration in its top end”. Tried twice, and failed twice, when developing the Roadster. So they gave up and went with a single-speed, fixed gear ratio system with no clutch.

There doesn’t seem to be any good reason to put a clutch into the Model S, or any other pure BEV. Spinning the motor itself doesn’t cause much friction, unlike an ICEngine, and you can provide the equivalent of a “neutral” gear by simply turning power to the motor off. Furthermore, the functional equivalent of a “reverse gear” can be achieved merely by reversing polarity on the motor so that it runs backward.

It’s interesting that both the Volt and the “D” version of the Tesla Model S use two electric motors to drive the car, albeit in very different configurations. But even when adding a second motor to the car, Tesla hasn’t needed to put in a clutch.


I don’t think Tesla needs a clutch. But it can use another gear to improve top end performance.

You don’t need clutch to vary gearing ratio.

Also, the common myth is that Tesla has too much torque that it would trash any multi-speed transmission. That is a typical false assumption by “hobbist”. The design of the transmission is a trade off between speed of switching, size, cost, weight and relability. Tesla’s choice by then might be limited due to those factors. But saying that it “can’t be done” is wrong.

The Tesla gearing ratio is about 9.74:1. So its max torque is around 4400 ft-lbs. I can assure you that you can find transmission that can handle it. But it might NOT be cost effective to put in the Tesla or it might NOT fit…

Jeff N

“Didn’t even use the word “clutch”, and there are five that allow things like the decoupling to run discreet series mode.”

The original Volt uses 3 clutches (2 clutches and a “brake”). The number of clutches in the new 2016 Volt transmission is a source of speculation and there is no definitive answer yet.


I think this is a revolutionary car! It was the first, to bad that it was not understood not even by its own people!


Yes, watched the video. This is clearly GM most Technically Advanced Vehicle Ever Built.

Jeff Songster

I like the VOLT… the reason I used to take exception to folks saying that it was an EV is mentioned in the op-ed. The reason it ticked me off is that the myth of no physical connection between gas motor and wheels is that it was used by GM so they wouldn’t be compared to Prius and look like a copy cat. The battery size and the clever ways they make the transitions make it better than the Prius. I would hear a sales droid at the car shows telling people that the gas engine was never connected… and that was nonsense. Do I think this was horrible? No… but I would rather GM told some truth once in a while.

Hi Jeff,

I don’t know that GM was intentionally misleading… They did make the above video, after all. However, I do think they have had a tough time describing the benefits succinctly, without people getting lost in all the details or only hearing terms they’re presently familiar with (like hybrid, and drawing the wrong conclusions, “oh, just a Prius”

Hopefully for the gen 2 Volt, they do a detailed analysis on the best way to market it simply and effectively, and hit the ground running.


I agree with Jeff Songster. GM shouldn’t have shortened the description to the point it was untrue. It’s a minor matter, though, and it didn’t stop me from buying one in 2012.

I must admit that it is hard to say anything about the Volt without it being slightly untrue. For instance, the Volt doesn’t get 100% of its full performance without its engine running, but only about 99%.

I would say a shortening occurs all the time in mainstream marketing, that often makes that abbreviated claim untrue.

The biggest example that comes to mind at the moment is LED TVs. They’re LCD TVs too, only the backlight is different. And yet manufacturers market them specifically as LED TVs along side traditional LCD TVs.

Now you can go read up on what an LED TV is, and realize it is really an LCD TVS with LED backlight.

I don’t think that means these TV manufacturers are misleading the public, nor do I think this means agm is misleading the public.

They’re trying to reduce the statement to what matters the most, and allows the consumer to easily distinguish the important differences.

If GM didn’t have videos like the above available for free access online, then I would agree they are misleading the public. But simplifying an explanation so the mainstream audience “gets it” is not misleading in my opinion, just like LED TVs

Jeff Songster

The other problem with the scenario is that it allows fleet buyers to greenwash their fleets with cars that never get recharged and drive entirely on gas. Apparently this has happened here and there. what a waste that is of great tech.


That is true. There are plenty of fleet Volts that are usually driven on gas.

But it’s not the Volt that wastes gas, it’s people who drive Volts who waste gas.

There’s so many claims being confounded here: 1) The claim that the Volt is not a hybrid. GM was adamant early on that the media not describe the Volt as a hybrid and the justification was that it operated like a series hybrid. When the production version came and people found out it was a series-parallel hybrid like the Prius, the media jumped on it and said “HA, I told you it WAS a hybrid”. 2) The claim that the Volt is an electric car / EV (while other PHEVs are not). Basically by inventing the EREV term, GM attempted to create a new category for itself, where it is grouped together with BEVs under the “electric car” banner, at the exclusion of the Prius and PiP. I see 2 reasons: to make-up for the EV1 backlash after WKTEC and to cash in on the public’s new interest in eletric cars after WKTEC. EV fans have felt it’s a hijacking of the “electric car” term, and the point was with under 40 miles AER, calling it an electric car only serves as an example to re-enforce the public’s stereotype that electric cars only have very little range. Also it’s unfair… Read more »
Jeff N

“When the production version came and people found out it was a series-parallel hybrid like the Prius, the media jumped on it and said “HA, I told you it WAS a hybrid”.”

I’ve never understood this line of thought…..

Obviously, a “series hybrid” is a “hybrid” just like a “series/parallel hybrid” is a hybrid. The hybridization aspect never changed. The Volt was always a hybrid from the early concept to the production car.

GM wanted to more accurately characterize the driving experience in the minds of customers so they chose to emphasize that it could be driven as if it were an EV until the usable battery power was used up by using the term EREV in place of “hybrid”. Unfortunately, that caused more rather than less confusion for some people.


If Toyota didn’t pollute the term hybrid, GM wouldn’t have to try to avoid that term.

Also, hybrid is used here to indicate “hybrid electric” vehicles which has electric in there by definition.

Calling it a hybrid is ignoring the fact that there are other types of hybrid that doesn’t involve electric powertrain.

Yes, because of the Prius, people associate crappiness with hybrids. GM needed to distance themselves as much as possible from that term. The Volt is an EV first, hybrid second (and a distant second at that).


I never understood it either, but this was a subject of much argument over at GM-Volt.com (and probably other Volt forums).

There was a lot of argument over whether the Volt met the SAE definition of hybrid:
“A vehicle with two or more energy storage systems both of which must provide propulsion power – either together or independently.”

One side interpreted the definition to mean that a series-parallel configuration to be the only configuration to meet that definition because they interpret that as the mechanical power sources (ICE and electric motor) having to provide propulsive power together or independently. Under that definition, a series hybrid is not an SAE hybrid.

However, the other side says that obviously a series hybrid is a hybrid (that’s where the term comes from). And the SAE definition specifies two or more “energy storage systems” (gas tank and battery), not talking about mechanical power sources like ICE or electric motors. Under that definition, both series and series-parallel configurations still qualify as SAE hybrids. The latter should be the correct definition.


JakeY +10

Eric: That’s an excellent analysis, thanks! As others have noted, you did yourself a disservice by labeling it mere “opinion”. I confess I’m one of those who has, in the past, groused in the past about the Volt not being a “pure” series hybrid. But the issue, or at least one of the issues, is that GM originally said it -would- be. They later claimed they said that just to protect their patents, which makes no sense to me. Why lie about it… and how did that help them protect their patents? In fact, how did claiming the Volt was a pure series hybrid help them in any way against their competitors? I don’t see that it would have. And lying to potential customers just makes us suspicious of anything else they claim about the car. So that’s the issue, at least for me; not nit-picking about semantic terms, but a lack of honesty by the auto maker. The other issue, regarding “Is the Volt really a series hybrid?” is the relatively poor gas mileage. Only 37 MPG as rated by the EPA, in a car which is supposedly engineered to be super-efficient? And it takes Premium gas to achieve… Read more »

The relative poor mpg of 37mpg can be explained by many factors:

Weight due to battery (majority).
Wider tires.
More performance
Slightly lower aero
Non-Atkinson cycle engine.

Premium fuels has NOTHING to do with MPG…

Bill Howland

My Amante got worse mileage with regular gas since the anti knock software would retart the spart to prevent predetonation. I suspect something similar is going on here too…


Sure for an engine designed to run on premium.

But saying that premium fuels should get more MPG is absolutely false. Premium fuels are typically designed to reduce knocking for high compression engine which might or might NOT relate to MPGs…

Bill Howland

my 2011 volt was designed to run on at least 91 octane. I cheat and use 89, but I think I’m killing my mileage a bit for the aforementioned reason.

Thanks Lensman, I suggested removal of the “Op-Ed” prefix, but it didn’t make the final cut. 😉

Jeff N
“So, it seems that I’ll grudgingly have to concede GM made the right decision in engineering the Volt to work in parallel hybrid mode when the battery is mostly depleted -and- an unusually high amount of power is required.” It’s intuitive for many people that the Volt switches to its parallel mode when high power (torque) is required. However, that is backwards from how it actually work. In reality, the Volt uses its parallel mode under low power (low torque) conditions like when it is cruising down the highway or county roads over 37 mph. The Volt is in parallel mode most of the time it is over 40 mph and the gas engine is running. This is according to a technical paper written by the GM engineers who designed the transmission and it has been confirmed by owners who have diagnostic displays hooked up to the car’s OBD-II port. Under high power conditions like maximum acceleration or when it is rapidly climbing a long steep road the Volt will be in (or switch to) series mode where the engine just spins the generator. The reason it does this is because the electric motor has a higher output rating (149… Read more »

“Series mode is less efficient and this explains much of the reason why the Volt gets lower city mpg than highway mpg. For example, the Volt is 35 city and 40 mpg highway whereas many other full hybrids like the Prius or Ford hybrids have higher city mpg EPA estimates.”

I’m not sure how the EPA does the test, but in practice that’s not really true. In fact, under 37mph, the Volt can often get over 50mpg in charge sustaining mode. I assume this is because the inefficiencies avoided by turning off the engine some of the time more than offset the efficiencies gained in the parallel mode. At higher speeds, though, the engine couldn’t turn off nearly as much, making the parallel mode most efficient.

Jeff N
Like the Volt, the Prius can also turn off the engine and run entirely on battery power at lower speeds such as under 37 mph. But, the Prius can additionally run in a very efficient manner with the gas engine running at vehicle speeds under 37 mph where the Volt has to run less efficiently in series mode when the gas engine is running at those vehicle speeds. At steady speeds around 30 mph, the Prius can probably get around 70-80 mpg. This is why the Prius ends up doing better on the EPA city test during the lower speed parts of the test cycle. Actually, even the Volt can get 70-75 mpg at a constant 45 mph (in series/parallel mode) if run that way over long distances according to a US government laboratory test. The design details of the Volt’s output-split series/parallel mode just doesn’t allow it to run that way at lower speeds (much below 37 mph) the way the Prius can do it with its input-split transmission design. These are design tradeoffs that allow the Volt to operate in EV mode at high speeds where the Prius cannot. Perhaps with the new 2016 Volt GM has found… Read more »

I think the other reason the Prius does better on the test cycle (though I’m just speculating) is because the Volt’s engine is not running nearly as often comparatively.

At least that’s certainly why the engine MPG numbers on the Volt appear lower in practice, because the engine is rarely used.

I admit though that I am not familiar with the particulars of the test cycle.

(in other words, the engine in the Volt is not warmed up to optimal operating temperature as often in the cycle)


That is true.

Also, the gearing between engine to wheel is different between Volt and Prius.

Volt’s engine is geared up to the wheel (engine rpm is lower < drive shaft) where Prius's engine is higher speed than drive shaft. That difference means the Volt's engine can't operate the wheel independently at low speed due to the torque requirement where the Prius engine would be operating at a higher RPM, but due to Atkinson cycle tunning which can be more efficient or at/near its max torque point…

Jeff N

There is no fixed gearing relationship directly between the Prius engine and the drive shaft. Although there are static gearing relationships between the 3 planetary gears, the dynamic speed of the Sun gear determines the effective gearing ratio between the gas engine and the drive shaft.


The point is that in the Volt, the sun gear “has to” modulate the variable ratio to the drive wheel b/c it doesn’t have enough torque due to “lack of reduction in ratios”. But in Prius, even if the sun gear is braked by generator or modulated slightly, the engine is still “geared up” to the drive wheel. Also, the Prius’s generator powered sun gear can NOT power the sun gear indefinitely due to lack of battery power thus it is designed to be powered by engine alone when the generator is in “braking mode”.

I don’t think most Volt owners ever defended whether Volt is series or parallel hybrid in the CS mode. Volt is both and more.. =) The fact is always been the contention such as EREV. By definition, GM coin phrased it so it should be defined by GM as Volt. Secondly, some BEV purist just hate GM and Volt so it would find any NONSENSE to criticize it. Thirdly, even if we humor the argument, the fact of the term EREV is really more defined by the EV portion rather than “extended range” portion. Even when Volt starts the “onboard gas heater” due to cold, it was started for heating reason, NOT propulsion reason. Even the BEV built by Volvo in the 70s had used Kerosene as heaters for BEVs. So the Volt’s EV mode basically matches all BEV description and definition. Lastly, the ONLY knock you can hold against the Volt for being EREV is the fact it does allow you to put it in a hold mode which somewhat defeat the definition of EREV somewhat since the battery isn’t “depleted” yet. That is probably why ever since 2013, GM has backpedaled a bit in holding the strong EREV… Read more »

The reason that GM doesn’t want to call Volt a “hybrid” is due to the fact that People confuse “energy source” vs. “powertrain configuration”. Prius is by definition a gasoline car but a “gasoline electric hybrid” in terms of powertrain.

Volt is by definition a “hybrid” energy source car (EPA label for 2011 Volt was “dual source”), but a mix mode gasoline electric hybrid in terms of powertrain in CS mode but a pure EV in EV mode in terms of powertrain.

So, Prius has “polluted” the word hybrid for too long.

Lastly, why do we call electric bicycles “electric” while it is technically a hybrid? Or Parallel hybrid by definition.


If you have a spare day or two, put on a few pots of coffee and read through the Pure BEV Dogma thread at TMC.


There, people have looked at this from every angle, sometimes from angles that are only visible in higher dimensions.

It does give some insight into where people are coming from on this on all sides of the issue.

Malcolm Scott
A timely discussion as it would appear that the Gen 2 Volt in range extending mode will have an expanded parallel/power split performance envelope compared with Gen 1. GM no longer has to act in denial just to maintain a political/marketing posture. It will be interesting to see how a 120kg lighter Volt operates in ‘Charge Sustain’ mode with a lower generator capacity whereas the engine is more powerful at higher rpm. What changes have been made to the normal and mountain mode buffer reserves with the battery? On the same long hill in charge sustain with 4 people on board with luggage, will Gen 2 be more capable without selecting mountain mode, or will the 53kW generator in Gen 1 be more capable? The Outlander PHEV operates in a range of parallel, series and ICE fixed drive modes, so no doubt the discussion will continue. PS. If anyone knows how to break into the Volt’s control configuration screens to toggle whether mountain mode exists for you to select, please let me know. Australian market Volts don’t have the option to select mountain mode – strange but true. Its there, but just not selectable. A few times I’ve come across… Read more »

LOL……that’a a whole lot of words……

But the fact is that if the vehicle can run on all electric power, along with a gasoline engine that can turn the wheels, it’s a plug-in hybrid. PERIOD! No matter how complicated or inefficient the energy transfer to the road actually is.

This marketing lie is what GM in trouble at the Volt launch. Then they bought their own lie and tried to compare the ELR plug-in hybrid with the Tesla Model S, and we all know how that worked out. 2 years of unsold inventory.

The current Volt is a longer range plug-in hybrid with poor hybrid mpg, but the 2016 model should put it at the top of the plug-in hybrid food chain. At 50 miles and 40+mpg, it’s a better option than 15 EV miles and 50mpg, when 50 EV miles allows for EV Only driving on a daily basis.


Why do we call electric bicycle electric, but NOT hybrid electric bicycle?


Easy. By definition, a bicycle allows pedaling and is human powered. An electric bicycle allows both the electric motor and the human to power it. Calling it a “hybrid electric bicycle” is redundant.

An electric two-wheeled vehicle that doesn’t allow pedaling would be technically called an electric motorcycle.


So, calling an electric bicyle that is technically “hybrid electric” is redundant but calling Volt a PHEV is NOT redundant?

If we call electric bicycle “electric” instead of “hybrid”, then Volt should be called “electric” as well.


That’s a false equivalency. Calling the Volt a PHEV is definitely not redundant vs calling it “electric”. PHEV specifies that it has both an electric ESS and a ESS that supports a conventional ICE, and also that it can plug-in. Calling it “electric” is ambiguous (most people would assume it’s an actual electric car AKA BEV).

While for an electric bicycle, there is no ambiguity: electric refers to the battery+motor and bicycle refers to something you can pedal. Adding in “hybrid” is not necessary.

Calling the Volt “electric” is only correct if you are using that term in a context where you would call the Prius (both plug-in and hybrid versions) “electric” too. I touched on that in previous posts (where EV refers to “electric drive-train” not “electric car”) I’m pretty sure you aren’t talking about that context though.

I always chuckle when people call 40mpg Hwy or 38mpg combined “poor”.


So all PHEVs are EREVs or is it he opposite? When a PHEV begins to be an EREV? With one mile of range? Ten? Thirty?

Just to add a little confusion, when I bought my Prius, I went on Prius Chat and found some hacks.
With one, I simply added a button and get 2 miles of AER with it. Is my Old Prius an EREV?
More, i found on youtube some serious hackers who messed with the computer and went to 70mph with their Prius on electricity only. Some third party sells kits to add batteries and go 30+ AER miles with a Prius.
So all HEVs are potential EREVs and all PHEVs are also EREVs.

The only thing I am sure is that the i3 is the only series hybrid on the market today, and its Range extender sucks.

Ha, former Prius owners. NO wonder! No, they aren’t all like. If the Prius can sustain even 1 mile or 2 miles of PURE EV range with about the same performance, then it would be technically an EREV. But it can’t. Sure, it can slowly drive up to 70mph, but that is its typical performance. We can argue this to death b/c someone will point out the slight performance difference between REx mode and EV mode of the Volt (0.2 secs due to extra electric power generated combined with peak battery power). But the same can be said for Fisker Karma where the Sports mode would have engaged the engine to generate extra power for the electric motor. But for all intense purpose, the Volt’s EV mode is no degradation and Volt is set to be EV by default. So, if you “modify” your Prius Plugin so it will drain the battery in 3 miles but with no performance degradation as it “hybrid” mode and it is default to EV only operation every time it starts the car, then it will be technically EREV as well. That is why Ford Energi cars aren’t considered as EREV but PHEV. As far… Read more »
“That is why Ford Energi cars aren’t considered as EREV but PHEV.” Wrong. By GM’s definition, the Energi cars are EREVs because they have an “EV Now” mode that allows it to operate without the engine kicking in even with accelerator input (the definition does not specify it has to be the default mode). And in terms of acceleration, all the car has to do is match CARB’s internal document of what qualifies for highway travel. From the recent roundup, the Energi certainly qualifies, as under that mode, the 0-60 of 15 seconds matches that of the iMIEV. http://insideevs.com/plug-vehicle-cross-section-acceleration-30-mph-60-mph-ev-mode/ The car does not have to have peak performance in EV mode to be an EREV (otherwise both the Karma and ELR would be disqualified because there is a big difference in performance in EV mode and with the ICE on). “Calling EREV just another PHEV is like saying Fuel Cell car is just another Hybrid or the Tesla’s concept of Lithium air range extension battery idea just another PHEV.” A fuel cell car with a traction battery/capacitor is by definition a hybrid (at least for the ones so far; it’s possible to build one that is not a hybrid, but… Read more »

“the Energi cars are EREVs because they have an “EV Now” mode that allows it to operate without the engine kicking in even with accelerator input”

I thought even with EV now mode engaged, under severa loading and elevation gain, the car would switch to “hybrid” mode…


No it won’t, I think you are thinking about the PiP. In EV Now mode in the Energi, the ICE does not turn on unless you confirm to allow it (it will ask you for confirmation).

“So all PHEVs are EREVs or is it he opposite? When a PHEV begins to be an EREV? With one mile of range? Ten? Thirty?”

As the article and others state, an EREV is a vehicle that can operate on electric only for some amount of range WITHOUT sacrificing acceleration performance or top speed.

It’s physically impossible to hack the Prius to give you those characteristics.

Bill Howland
“….at speeds above 37mph and under reduced power loads, the Volt can indirectly link the engine to the wheels…” You’ve said this a few times now. What I was told was that my volt locked up ‘somewhere’ (due to proprietary information – a dumb restriction in my view) around 66-70 during steady-state driving. Please document the 37 mph since it goes counter to any information I have seen. The video is also in disagreement with my owners’ manual. There it says 100 mph is only possible with the engine running. Instead of these videos which don’t clearly show what is happening, and have no power flows anywhere, they could document typical operation in each mode on a single 8 1/2 x 11 sheet of paper, but I have as yet to see a clear explanation of precisely where transitions occur and at what power levels, probably due to some silly proprietary restriction. This has the smell of GM ‘saying’ they’ve explained how the thing works without saying much. Kinda funny since in the 2011’s at least, they bought the thing from the same Toyota subsidiary that makes the Synergy Drive, and its no surprise because Toyota probably designed the whole… Read more »

I guess the fact that I see the switch-over during every gas-extended trip on my 2013’s instantaneous power display is insufficient. Standby and I will search for the graph. 😉

Also, regarding speed, I’ve gone 100mph in both EV mode and with the engine, so it is absolutely possible. In fact I have a picture of that somewhere too, haha.

Here you go Bill: http://gm-volt.com/forum/showthread.php?6611-Voltec-drive-unit-has-four-basic-modes-of-operation&p=58302#post58302

It is straight from an engineer at GM that frequents the GM-Volt threads.

As you can see in the second graph, the “Combined 2 motor ER” mode starts at 60km/h, which translates to 37mph.

There’s also some other figures throughout that thread that you may find interesting, if you have the time to peruse it.

Bill Howland

Ok then please specify its the 2013 you are talking about. This video is from a 2011, and as my car is, I believe that the 2011’s are all basically toyota equipment.

The desire was to quickly get all this stuff done in Michigan, so no doubt they tinkered with the design, and, at least with the 2016, you would think they’d want to stop paying royalties to Toyota, since even they can’t claim to have invented a planetary gearset. But they could claim the 2011 design was theirs since that would make sense, but again your 2013 I’m sure has much more “American Content”, and I would assume the upcoming 2016 is even more designed ‘in – house’, to avoid nagging royalty payments.

Did you go 100 mph in a 2011 on the battery? My owner’s manual says thats impossible, unless you are going downhill.

Hi Bill, the link I reference above showing the speeds is from Feburary 2011. As mentioned previously, the inner workings of the Voltec drivetrain have not changed between 2011 and 2015.

“Did you go 100 mph in a 2011 on the battery? My owner’s manual says thats impossible, unless you are going downhill.”

Yes, I did go 100mph on the battery in my prior 2011, and not down a hill. I suspect you’re either recalling a statement incorrectly, or there was an error in some revisions of the manual. There’s an online PDF of the 2011 owner’s manual available; any chance you can reference where you saw that?

I’ve never seen that limitation noted in my owner’s manual (on one of the first 2011’s delivered) but I never looked hard either; I got my answer when I went 100mph in it. 🙂

Bill Howland

look at my dept of energy stuff down lower here. Thats where the 98 mph figure must have come from. I’ve looked over alot of data and find that some of it (not the doe, which seems decent)is not too tight all the time, for instance in one place they say a 40 amp circuit is required, and another 30 amp, whereas GM has always stated a 20 is required with 40 for the future. But my window sticker says the transmission is from japan.

Hi Bill,

Well, you and I were not debating the transmissions source, though I would strongly disagree with the claim that GM used a Toyota transmission. Where is the reference for that??

I also think Jeff’s post, if you re-read below, describes why the sticker may say Japan.

Jeff N

This is the patent that describes the transmission used in the 2011-2015 Volt’s. The design has not changed until the new 2016 Volt which was recently shown at the Detroit Auto Show. This patent was filed in 2007:


Jeff N

Every GM transmission has a manufacturing label affixed to the outside. If you really want, you can crawl under your car and look for the label on your 2011 transmission. It will have some code numbers on it.

There is a diagram in the 2011 Volt service manual that describes how to decode the numbers. One column contains a digit indicating the manufacturing plant that made the transmission. None of the possible enumerated manufacturing plants with their different assigned label codes are located in Japan. There is a code number assigned for Ramos Arizpe, Mexico which is where the 2011-2015 Volt transmissions were all manufactured.

Jeff N
Well, I popped the hood on my 2011 Volt and it doesn’t look like the label is easily visible. In any case, there is zero evidence for your theory that early Volt transmissions were made by Toyota. None. Didn’t happen. For example, I bought the official GM 2011 Volt service manual — all 3 volumes of it. Chapter 17 in volume 3 is all about the transmission. It is 362 pages long and contains detailed drawings of every single part in the transmission and textual descriptions and clutch shifting logic tables describing how it all works. This manual is specifically for 2011 Volt’s and the details are completely consistent with the 2007 patent I linked to in an earlier comment and that is the same design used in all model year Volt’s and in the ELR. Although this transmission implements an eCVT power-splitting scheme, the details of how it works is very different from anything Toyota or its Aisin subsidiary have ever built. As described earlier, the window sticker says the transmission is from Japan because the high valued parts of it — the motors and inverter electronics, were made in Japan by Hitachi even though the actual complete transmission… Read more »
Jeff N

The InsideEVs article is accurate. The Volt’s parallel mode kicks in at speeds as low as 37 mph. Also, the gas engine does not have to be running when the Volt is going at its maximum speed of 100 mph so I suspect the owner’s manual does not actually say that. Please site which model year owners manual says this and at what page…

The transmission operation is not secret. It’s detailed in an SAE technical paper published in April 2011. Unfortunately it is behind a paywall but you can download it for $20-30 if you are really interested.

Here is a link to a discussion about that SAE paper including some graphs taken from the paper that indicate the speeds and torque levels at which the transmission switches between its various modes. Read the graphs carefully since they are in metric (kilometers per second instead of mph etc.). There is also a link there to where you can purchase the actual technical paper:


Jeff N
“This has the smell of GM ‘saying’ they’ve explained how the thing works without saying much. Kinda funny since in the 2011′s at least, they bought the thing from the same Toyota subsidiary that makes the Synergy Drive, and its no surprise because Toyota probably designed the whole thing anyway. But I would doubt GM admits that for public consumption.” Wow…. That’s all totally false. Actually, GM filed a patent in about 1996 describing how the original Prius transmission works before Toyota filed their US patents and before the first Prius cars were delivered to customers in Japan. The Volt transmission was never made by Toyota or a Toyota subsidiary. You are thinking of Aisin which manufactured the original Prius hybrid transmission using Toyota’s design and which also manufactured Ford’s original hybrid transmissions (Ford Escape Hybrid). Both Toyota and Ford now do their own transmission manufacturing. The Volt transmission was never made by Aisin. The Volt EPA window stickers say the transmission originates from Japan and that has confused some people. Actually, the Volt transmission has been manufactured at a GM plant in Mexico but the motors and inverter electronics that are part of it are made by Hitachi Automotive… Read more »
Jeff N

Here’s GM patent, filed on February 17, 1995 which describes the Prius transmission design independently developed by Toyota around the same time (search for the “third alternative embodyment):


Jeff N

Mexican news article (translated via Google) about GM plants in Mexico and what they manufacture. The Volt’s 4ET50 transmission is made at the Ramos Arizpe plant as shown near the bottom of the article:


Jeff N

2011 Volt electric motors and inverter made by Hitachi:


Bill Howland

My window sticker says the transmission was made in Japan.

This may have been a temporary situation, but I’ll go by what the info there says over your information, no offense.

The U.S. dept of energy site, says that the 2011 volts top speed at a 3% grade was 98 mph in ‘charge depletion mode’, and is 100.2 mph in ‘charge sustaining mode’.

THis must be where the 98 figure came from.

In glancing over this stuff they now say for modern volts 30-70, but initially it was stated 66-70.

Jeff’s comment above didn’t deny it says Japan, in fact he agrees. Rather, he was trying to elaborate on why it said that:

“The Volt EPA window stickers say the transmission originates from Japan and that has confused some people. Actually, the Volt transmission has been manufactured at a GM plant in Mexico but the motors and inverter electronics that are part of it are made by Hitachi Automotive Corp. in Japan.”


All EREVs are by default PHEVs. The reverse does not hold true though.

Simple test to determine if a PHEV is also an EREV: crank the heat to the max with the defroster on, and floor it. Do it with a full battery and nearly depleted battery. If the ICE doesn’t switch on, congrats, you have an EREV!




The i3 rex does not suck. BMW tried to play the classification game the same way GM tried in the volt. The i3 Rex sold in the U.S. is hobbled by regulations trying to count more as a BEV for credits and hov.

If the i3 where allowed to run the Rex while there was significant charge in the battery, the way they do in Europe and the way the volt does, the Rex would be fine.
You don’t need that much power all the time unless you’re driving up the continental divide. A decent size buffer and you could comfortably drive long distances at high speed and up hills, like the volt does in mountain mode.


Tesla had the idea on using a different type of battery (lithium air or alumnim air) to extend the range of BEV. If that is the case, then technically they are also PHEV by definition due to two different hybrid energy source.

Fuel cell cars are technically hybrid in powertrain design. If you add a plug, then it can be either an EREV if battery is sole power until it is depleted or a PHEV if both are used by default.

So, as we can see, the terms are getting far more complex than average people can understand. We should support any kind of electricfication as they are the best improvement in efficiency thus reducing oil usage.

To add confusion, I believe it was Fisker who called their setup EVER. Electric vehicle with extended range.


Meh. There are no solid generally agreed-upon definitions of EREV, PHEV, etc.

Bill Howland

The cardinal sin here is GM LIED, even to their dealers, for the first 18 months.

So even though they are more truthful now, their initial ‘obfuscation’ shall we say? confused the matter unnecessarily.

Maybe, for marketing purposes, they WANT the confusion for some silly reason.

But the general consensus is, the Marketing of the Volt has to date done by a bunch of DIM BULBS.

The problem is, it is impossible to succinctly describe something that is intricately complex with a lot of conditionals.

While you and I may be fascinated by the details, the mainstream buying public just wants to know what makes this vehicle better than others. If you go into all the nuances, you’ve lost a sale, as they won’t retain anything but “wow, that was too complicated for me to understand.”

Bill Howland
In any technical class I’ve been to over the years, the professor or whomever was teaching it would invariably embarrass me by saying “thats such a small detail, why would anyone have to know that? (meaning of course, that they either didn’t understand my question, or they were too lazy to find out). Of course, when the equipment broke down, then, of course I was instantly expected to know everything about it, which in some cases I actually got awards, and the enginerring group for Verizon told my boss “there is no man in New York State who knows more about the At&T Ess 101”. So asking simple questions sometimes helps. None of us would have to use conjecture if they’d only say it. And they don’t have to put the info on absolutely every sales brouchure, but if it wouldn’t hurt if they did it on a few of them. We disagree only in the atmospherics. Planetary gearboxes aren’t that challenging to understand, although the gm-volt site did say ‘at least 30% torque from engine’ when getting 10-15 % improvement. This gets into the tweaking argument I was mentioning a few days ago, but even I don’t see how… Read more »
Bill Howland

“… The problem is, its impossible to succinctly…..”

Thats a different issue. GM did not have to lie.

Even this use of the term indirect is deceptive. I suspect that wording is related to ‘keep the lie propped up’, or its an unfortunate coincidence, which I kinda doubt.

What was the specific “LIE” you speak of? There is no direct mechanical linkage, only an indirect one.

(and all this “GM LIED” talk reminds me of “BENGHAZI!” talk)

Bill Howland

Well, Clarkson said that statement but I think its rather like you have to “Listen to what he means not what he says”. There is a direct, mechanical linkage at either 66-70 mph, as was initially stated, or 30-70 apparently for the more modern volts.

At that point, steady state, there is a direct, mechanical coupling, albeit the generator at the time is also siphoning off some foot-pounds.

Bill Howland

But GM definitely lied the first 18 months. They would get brownie points if the thing was clasified as an electric car instead of a hybrid.

They told the dealers the thing was a genset. At Fucillo Chevy the head mechanic told me,

“You have no idea what youre talking about!”

(Where have I heard that before, – just about with every blog here ).

“Im expert on VOLTEC, they sent me to one week’s training on it. 100% of the power from the engine goes to the generator at all times.”.

I said, “OK, what is clutch #3 for?”

After a long, pregnant pause, he said, “You know, they NEVER did tell us what that was for, i’ll have to look into this further”.

“100% of the power from the engine goes to the generator at all times.”.

Bill, if this isn’t true, you need to depict and cite with references how the engine gets its power to the wheels without using the motor-generator as a carrier. Otherwise, that statement the tech made is accurate. In all modes the engine is running, it remains directly linked to the motor-generator. Whether or not that generator is generating electricity or driving the wheels is really the point you’re trying to make, but the tech’s statement seems accurate in my opinion.

Bill Howland

Thats what the mechanic said, so it must be right.

Seriously, I think you are reading my posts too fast. When you read them more slowly, you seem to understand.

No, I just think you’re implying something from his statement that he isn’t inferring. If he said all energy went to the BATTERY 100% of the time, he’d be wrong. But the electric motor used to link the engine to the wheels is the thing that acts as a generator, so his statement seems more true than false.

“There is a direct, mechanical linkage at either 66-70 mph, as was initially stated, or 30-70 apparently for the more modern volts”

Bill, I’ve provided you references that prove this is false, including diagrams from 2011 that show the 37mph switch point. There is no ‘more modern Volt” aspect of this detail, it is on all Volts.

I’ve provided references as you requested, direct from GM personnel and Jeff has provided patent documents showing the operation of the transmission is unchanged.

If you still feel I’m wrong, I would like to have you provide some alternate references, with links, as you required of me.

And whether or not it is a direct or indirect link is dependent upon how you define it. Without the electric motor clutched to the generator and to the wheels, the engine cannot drive those wheels. Hence indirect.

Bill Howland

Your and my definition of the word direct and indirect are apparently different. What diagrams are you referencing?

I posted them earlier and you didn’t see it apparently, who is reading too fast? 🙂 37mph switchover charts from 2011, as posted above: http://gm-volt.com/forum/showthread.php?6611-Voltec-drive-unit-has-four-basic-modes-of-operation&p=58302#post58302

Chief engineer Andrew Farrah on the indirect link:
“There is no “direct” mechanical linkage between the Volt’s gas engine and the wheels, rather there is an indirect linkage that is accomplished by meshing the power output of the engine with the power output of one of the other two electric motors.”
Source: http://www.plugincars.com/exclusive-chevrolet-volt-chief-engineer-explains-volt-drivetrain-says-volt-electric-vehicle-90758.ht

Bill Howland

I don’t have access to the first link.

The second plugincars link stated Motor Trend was wrong in reporting 70 mph is a hard and fast number, that its a range, but I remember Motor trend said it started somewhere between 66-70, eg, a range.

Not having read much of his stuff, Farrah might not have the nack of explaining simple concepts in plain english, which is somewhat surprising, but then again, in fairness to him I didn’t read what he said this time. The only thing I remember about Farrah is the cringe he’d get on his face when “Head Engineer” Fletcher would talk about “Reactionary Forces”.

Bummer that you can’t see the GM-volt.com link. It has a lot of great info in it beyond the speed diagrams that I think you’d find interesting.

I’ll see if I can find your email address (don’t remember if I have it) and mail you the images directly.

Bill Howland

Got the links, thanks. They spent a lot of time drawing pretty pictures, but it would be much easier if they’d just say, Sun, Spider and Ring.

We each have our preferred form of measurement, but why they use the metric system in the States I’ve always found puzzling, but then EE’s are still taught electricity goes from pos to neg. Other than hole currents in transistors, I’ve always thought that was a convoluted explanation, mainly due Ben Franklin making a mistake a few hundred years ago.

But its easy to see if they really meant 56-60 kilometers/hour.

There was one space probe launch that went way off course about 10 years back because one contractor used english measurements and the other metric, and they weren’t sufficiently deliniated. SO this kinda stuff does have costs.

Bill Howland

This is unbelievable. I didn’t say that. Please re-read my post.

Didn’t say what? I copied and pasted, look at your post above at 1/23 4:38pm. That’s what I was replying to and quoting, and that is what you’ve subsequently replied to here. I don’t think I’m confusing the reply threads here, though they get hard to interpret at depth.

“There is a direct, mechanical linkage at either 66-70 mph, as was initially stated, or 30-70 apparently for the more modern volts.”

It’s all good though Bill, I’m not raging or anything and still want to do ice cream again sometime. 🙂

Bill Howland

Jeez, after getting to know someone for a while you get to know how a person talks and when he says something you instantly translate it so that you understand what he’s saying.

This whole conversation has been me saying,

“I don’t know why they did it that way, who knows?”.

NOSE? whats wrong with my NOSE? ARE YOU SAYING YOU DONT LIKE MY NOSE????!!!!

Haha, awesome. 🙂

Bill, dont you think it is important to speak very precisely about the claims in a thread that is criticizing GM for not speaking precisely enough?

I have to trust their chief engineer in their description of indirect. It seems like he would know best, and with all the patents out there, he has no reason to lie in a detailed techie non-mainstream-marketing scenario.

Bill Howland

To me its sloppy use of words which have plain meanings, and I’m in general not found of GM’s engineering, although the VOlt is definitely a feather in his cap.

My 2011 used to constantly have software bugs, but they did do one software upgrade back when they recalled the vehicle for mainly the battery shielding. So, it was obviously released before being ready, but at least they substantially fixed it, a good thing.

Engineering specifically refused to speak with me personally, although they did speak to the dealership. I thought that was unbelievably arrogant. But then they did have a few more warranty repairs they had to pay for that they wouldn’t have if they had deemed to get off their high horse.

Some of these guys they need to dock them a few days pay to give a much needed ‘attitude adjustment’.

Emailed you the images!

Interesting, when k had problems with my 2011 early on, I spoke with an engineer at GM who contacted me, and even Mickey Bly, who reached out to me directly and offered I call him if I have any more issues.

Regarding the software bugs, the majority of that user interface is done by contracted companies I think. Still not excusable, but hard to speak to a GM engineer about software if much of the UI came from contractors.

Bill Howland

I dont want to do Lunch until the weather gets better since I need dry roads. I spun out in the roadster going 25 mph when i hit a patch of snow. no damage, but I’m pushing my luck.

That makes sense. I had assumed you wanted to wait. Once summer rolls along I’ll also be done my MBA, which should give me some more flexibility in my schedule too.

Bill Howland

No, no, no, this is micro splitting of hairs.

When I said its not going through the generator, i meant 100% of the power is not being transformed.

Literally, I would guess you could make the technical point that the generator SHAFT takes 100% of the power, which is technically true.

But that was obviously not my point so I don’t know why you waste time bringing it up?

Saying the energy is not always TRANSFORMED is a different statement. As mentioned above, the link is always engine-motor-wheels, hence indirect.

You can say I am splitting hairs, but I’m not one of the vocal people up in arms that GM lied about this mini micro detail that only provides more fuel efficiency. That seems like splitting hairs. 🙂

Bill Howland

Ugh. I give up. Lets agree to disagree.

Haha. If nothing else, this whole thread serves as an excellent example of why GM should water down their technical descriptions to the mass market.

We’re you able to review the diagrams of switchover speed in the link I referenced above?

Bill Howland
Yeah thanks I read the article and the sub article which states “the stators are the same but the rotors are different”. Wish they would use precise terminology since they just waste words and cause confusion when they, in an equal number of words, say exactly what the situation is. On the DOE filing of the 2011 volt, then mention the motor is 16 pole, and the ‘generator’ which i put in quotes because it is either, has 12 poles. Common terminology is to ignore 3 phase complications, namely 16 poles would in general mean 16 sets of poles, but not sure if they are adhering to convention here. If they are, then 16 poles on the motor would mean 450 rpm @ 60Hz and 600 rpm @ 60 hz on the motor/generator. So a maximum speed of 6500 rpm would be 866 2/3 hz. That seems ridiculously high and I would think hysteresis losses would become a problem. All teslas to my knowledge only have 4 pole machines, to keep the inverter frequencies reasonable. But GM for some screwy reason may be inventing their own language, which makes a vaguely worded article about as clear as mud. So what… Read more »

Well, the article wasn’t written by GM. Sounds like what you really want is to hear some of their SAE paper presentations coming up. That would be fun.

Bill Howland

Yeah, I don’t know why equipment manufacturers talk about ‘direct drives’. If youve ever looked at a pop vending machine’s 1/3 horsepower ‘direct coupled’ cardbinator pump (located about 3/4″ from the motor) ….

Its obviously indirectly coupled as you say since there is a shaft in the way.

In the engine goes through a shaft AND a motor to get to the wheels in this parallel mode. I thought we agreed to disagree?

Unrelated, I stumbled upon this SAE article about the Gen 2 Volt that you may like. There’s some inaccuracies, but also a link to another decent (in my opinion) SAE article: http://articles.sae.org/13831/

Gah, supposed to say, “In the VOLT, THE engine goes through a shaft AND a motor to get to the wheels in this parallel mode.” But you probably gathered that.

Typing on an iPad while having a bad bronchitis doesn’t work well.

Bill Howland

Nope, don’t have access to them. The thing says ‘permission denied’.

TOO specific? To me they are hopelessly vague and wouldn’t want them to be more vague.

In other news, did you happen to find out what the AC current limit is on the 2016 charger? I’d assume still 16 amps, but it would be handy to know exactly what it is.

I haven’t seen anything on the current limit being directly referenced, but a high up engineer in a Gen 2 Volt FAQ stated the following:

Q) What is the charging rate in the Gen 2 Volt?
A) The Gen 2 Volt will charge slightly faster, at 3.6kW versus 3.3kW in the Gen 1 Volt. This will allow the Gen 2 Volt to charge in roughly the same amount of time as Gen 1 despite the larger battery.

Bill Howland

Yup we had that discussion sometime back. Now I wonder if jeff N will reveal why they bothered with a 10% change or whether they got a deal from Lear Or Spx, or Remy or whomever makes for the same price as the 3.3 kw.
I’m assuming the min input for full output is now 225 volts, up from the 206.25 in mine.

Now that would be practical, real world, actionable information.

Yes, I know we had already discussed kW… I wish I had the current limit answer for you!

Again, I have not heard the “LIE” that people keep talking about. Still waiting…

(I think the whole topic is fodder for anti-GM trolls)

Bill Howland

I’ve tried to answer this 3 times Kdawg but I keep getting jumped on , even by my friends.

Let me try one last time.

In the first 1 1/2 years or so GM was claiming in all their public statements that the engine only is a battery charger (as it truly is in the rexi3).

They at no time would allow anything else since they didn’t want to have the car classified as a hybrid, but rather as an ELECTRIC car.

This went on until a NY State employee at our dept of motor vehicles called someone at gm and said , ‘You’re not fooling anyone’.

It was only then that GM dropped the charade and released the above video, which shows the engine ‘helping out’ the wheels sans electricity.

Ok for all you dudes out there, I know that the volt has electricity in it!! and that motors are spinning. I understand that, please don’t bring it up again.

I’m glad you consider me a friend Bill (and likewise), but I am bummed that you felt you were being jumped on by me. Certainly not my intent!

Bill Howland

and if you look at my tongue in cheek carbinator pump example above, I can imagine Farrah’s boss (during the lieing time), “lets not talk about this Direct engine drive, lets deam it “Indirect”, – you could say there is a shaft in the way or other complications”.

“We don’t want any verbiage stating the engine ie REMOTELY connected to helping turn the tires”.

Give me a quote or a link of the “LIE”.


Gm lied when they crushed the EV1 (because a lack of spare parts)
They lied after the film “Who killed the electric car”, promising a new Electric Car BEV.
They lied when they presented the Volt concept, it has transformed in a 250mpg series hybrid.
They lied rolling out the final version, a multi mode hybrid.

They also lied in the rare adds saying that it was “the electric car that goes further”

I find the Volt a very good hybrid, maybe the best fro now, and I don’t give a damn if it is a pure series hybrid or a deep fried monkey juice engine that runs it.

The debate is about those companies that produced good range EVs in the late ’90s, then removed them (except for some of the RAV4) to be replaced by hybrids. It is a big step backward.
GM is the one who went as far as DESTROYING 1500perfectly good cars that people wanted, to persue their agenda of killing again the electric car.
They have now a great deal of the responsability in the regression of the fight against climate changes.



And Toyota crushed the Rav4 EV, and Ford crushed their Ranger EV, yet you only fault GM for it?

Some people hate things because of certain events or occurrences, and others look for events or occurrences to justify their hating something. Which camp do you fall into?


No Toyota acccepted to sell many RAV4.
For Ford I don’t know.
We see in “Who killed the electric car that Honda crushed some EV Plus.
GM is the leader in crushing their vehicles and lying all along.

No.. you are off topic. The debate is about the Volt, and understanding how it works.
“They lied when they presented the Volt concept, it has transformed in a 250mpg series hybrid.
They lied rolling out the final version, a multi mode hybrid.

They also lied in the rare adds saying that it was “the electric car that goes further”

Where are your examples of “LIES”.



“La voiture électrique qui va plus loin”


Sorry 230 mpg


BTW it’s not by insinuating that I do not “read/understand” that you will be more relevant.


And it is also me that introduced the link to the video of this article.



My Volt shows 250mpg every day I drive to work.

So, I guess it is doing better than GM’s 230mpg claims…

Are you confused about mpg and MPGe? Measuring efficiency and gas usage are two different things and can be the same on pure ICE cars.

Then again, knowing you and how much you hate GM, I am NOT surprised that you don’t get it…

Bzzz. Wrong. That’s not a lie. I get well over 230MPG.


There is are accepted definitions for PHEV, actually. SAE and IEEE both have one and they’re essentially the same.

EREV/REEV/EVER doesn’t have a standard definition. It is/has been used by various manufacturers and organizations over the years (Tesla, GM and the DOE for example).


Volt, Prius, and i8. Which one will be first to be offered as all electric?

Bill Howland

I think all those cars are fully electric, including the I8 ads.

The ads conveniently forget that people occassionally make more than 5 mile trips.

Its rather like I used to kid a friend who said “I thought all of Buffalo was 4160 volts? I’d say, since 25 hz was 0.1% of the customer base and 60hz 99.9%.

“Its all 4800 volts, except for the 60 cycle”.

Youre supposed to forget the fact that most of these cars lives live on gas, except for the volt.

Barra won’t commit either to
1). whose decision it is to make the Bolt.
2). whether it has been decided to make it or not.


205 comments on Inside EV article that explains about how Volt works just shows that even for EV fans, people still don’t get how Volt works.


M Hovis

Sad but true. So lets make it 206. There is a common thread between an i3 Rex and Volt owner. Both would rather drive on electricity ALL the time, but due to their lifestyle, they need an extender. This is less important to the large number of other parallel hybrid owners.

There really is something special about the all electric drive. It is about the experience. That is what the argument is all about. Some purest are trying to say, “you really don’t know this driving experience”. This is what winds a Volt owner up, for its acceleration, and handling is one of the best out there.
Want to pick on a Volt? Pick on its inferior heater (unless you change to HOld Mode), pick on its short head room.

Driving experience? Take an extended test drive and you will understand what all the fuss is about.

Bill Howland
As I’ve said before, they could completely if succinctly describe fully the operation on a single sheet of paper (Clarkson emailed me some curves as to operation mode switches, which helped greatly), but as it is they are so vague in their explanations and lack specificity, that I’m still unclear on some things, but then I knew before I bought the car 4 years ago basically how it works, and I’m still about there right now in familiarity. So I haven’t learned much in 4 years of ownership, but then I’ll live. It didn’t help that GM initially lied to customers and even its dealers as I’ve mentioned, and I don’t care if that is believed or not. This alphabet soup about what is what I couldn’t care less about. I hate abreviations in general. A certain amount of Jargon is necessary in technical fields, but the pedantic displays I can do without, since they confuse both the experienced and uninitiated.. The other universal issue is that if a person cannot explain in plain english what is happening, then that person doesn’t understand it himself. It may take longer than 10 seconds to explain, but then again I didn’t say… Read more »
M Hovis

I don’t worry about those of us who have driven EVs forever. I worry about those new to the game reading and trying to understand. I like the acceleration graphs that David Murray posted recently. I go nuts when someone makes the technical comparison of a Volt to a Prius. On paper, there are a lot of similarities. But like the acceleration graph, these two vehicles have totally different driving experiences. I bought my daughter a Prius. It fits her needs. But even she would tell you the worlds of difference between the two and she does not understand a thing about the engineering of the cars. This is not for you Bill because you know all of this. You should know by now I right primarily for the newbies, unless I write about energy and I go in the opposite direction.


Does it really matter that GM “misled or lied” about 1 tiny highly technical detail from a marketing point of view?

I am willing to bet that over 95% of the car buyers wouldn’t know the difference anyway even if you told them the difference.

I give GM a pass on it b/c the fact that if GM told everyone about the truth, then every “half bottle” full techies would think Volt is just another Prius. GM wants to avoid that and I agree with it.

Volt wants the distinction from Prius.

The closet similarity is actually the Accord PHEV powertrain…