Op-Ed: How to Solve the 1% Problem


According to Voltstats, the average Chevrolet Volt driver does about 75% of their driving on electric, and 25% on gasoline.  I have a Volt and for me it is more like 99% on electric and 1% on gas.

Chevrolet Volt - Well Equipped To The Occasion Trip To Nowheresville

Chevrolet Volt – Well Equipped To The Occasion Trip To Nowheresville

So the Volt has an EPA rating of 38 miles EV range.  Lets imagine that it had 60 miles EV range.  I bet the numbers would shift to where the average driver got 85% EV.  What about 80 miles EV range?  100 miles EV range?  I suspect at 100 miles range you would finally hit that average of 99% all EV driving and that 1% on gas.  The thing is, at this point you can continue to increase the battery range and you still have diminishing returns.  That’s because the 1% remaining usually ends up being road trips.  This is already the case with my Volt.  that 1% of gas usage is when I need to drive from Dallas to Houston, or Austin.

Time and again we hear the electric vehicle naysayers, as well as some potential buyers ask the question:

“What do I do when I want to take a long trip?”

Speed And Harsh Elements Are Not Your Friends On Long Trips In The LEAF

Speed And Harsh Elements Are Not Your Friends On Long Trips In The LEAF

Some might argue that with enough fast chargers, it would be possible to use a vehicle like the Nissan Leaf to do this.

And I’ll admit that having a reliable network of fast chargers would make it possible to travel to destinations around 150 miles away.  Even that would likely require 2 fast charges along the way.  Keep in mind that driving on the interstate usually infers speeds of 75 mph or more.  The Leaf’s range suffers horribly at that speed. Plus a 30-minute charge only gets you to 80% capacity.

I’m going to assume most of the general public would not be willing to stop every 50 miles for a 30-minute charge.  And I suspect even that would be cutting it close.  So what are the other alternatives?

One strategy is using a range extender such as the Chevy Volt.  This system works well, I can vouch from my own experience.  In fact, one of my trips to Houston I actually saw another Volt on the same road-trip going down the same highway.  The disadvantage is that the Volt is more expensive to build and a lot of EV purists won’t touch it because it has a gas engine.  And honestly, the EV range isn’t good enough to give the average person 99% EV driving.

Tesla has taken a different strategy.  Put in a huge battery and build a bunch of fast charging stations at strategic locations between cities.  The obvious disadvantage here is that the battery pack is very expensive, and the network of fast chargers isn’t really in place yet outside of California.

BMW i3 Tackles The 1% Problem

BMW i3 Tackles The 1% Problem

Enter the BMW i3.  There’s been a lot of talk about it lately, some of it negative.  But there is one thing about it I find absolutely brilliant.  They give you the option of a gasoline range extender for $3,850.  Now think about this for a moment.  With a 22 Kwh battery pack, and assuming a price of $400 per Kwh, BMW’s battery probably costs around $9,000.   That’s enough to give you 80 to 100 miles of range.  That should come pretty close to reaching the 99% barrier I’ve been talking about.

So which works out best for the consumer to solve that 1% issue?  Tesla would have you buy another 63 Kwh of battery, probably coming in at $25,000 more.  Or BMW would have you buy a small gas engine for $3,850.  For something that will be used 1% of the time, I think BMW’s approach makes more sense for a middle-class car buyer.

But the fact that the range extender is an option instead of standard equipment like the Volt also has some other benefits.  Remember how Volt drivers say they’d never buy a Leaf because it doesn’t have a gas engine. And Leaf drivers say they’d never buy a Volt because it HAS a gas engine?  Well, this car can appeal to both mindsets.  If you want the range extender, get it.  If you don’t want it, don’t get it.  The other benefit is that it lowers the entry-level MSRP, which helps get people’s attention.

If Money Is Not A Big Issue You Can Pay To Solve The 1% Issue With The Tesla Model S

If Money Is Not A Big Problem – You Can Pay To Solve The 1% Issue With The Tesla’s Fine Lineup Of Pure EVs

There’s another unspoken benefit of a range extender.  It actually increases the size of your battery, sort of.  When I drive our Leaf, I always try to leave 20 miles as a buffer. On occasion, with a well-planned trip I might leave as little as 10 miles buffer.  I won’t risk going lower than that.  Even at 10 miles, That’s nearly 13% of my battery capacity that goes unused.  On the other hand, when driving the Volt I don’t mind taking a trip that puts me at 1 mile remaining on battery when I pull into the garage.  That’s because I know that a detour or miscalculation on my part isn’t going to leave me calling a tow-truck.  So in many ways, having the range extender gives you more EV miles than you’d have otherwise.

5 Gallon Propane Tank

Propane Tank

There’s another curiosity that has been on my mind lately. According to my math, a propane cylinder like you buy at the supermarket for your BBQ grill has the equivalent power of 0.74 gallons of gasoline.  So I would expect in a lightweight EV with a small range extender engine could probably drive 30 miles or more on one of these things.

So if the hatchback (or frunk if the car has one) has space for 2 of these cylinders then you could probably go 60 miles.

Almost every supermarket, gas station, and pharmacy sells these things. It should be almost as convenient as buying gasoline. Yes, it would cost more than gasoline per mile (unless you refill the tanks yourself) but it would have some distinct advantages.  For one, it never goes stale. You can store the tanks for years. Also the engine won’t get gummed up from disuse (requiring a maintenance burn like the Volt)  Second, the tanks can be removed from the car when not needed, thus freeing up weight and cargo area.  And if the EV could do 80-100 miles on battery, you’d really only keep these around for that 1% usage, so the cost per cylinder isn’t that big of an issue.

So to summarize.  I think the idea of a small range extender is a win until the price of batteries drop to the point 200+ mile ranges are affordable for most people.  I would like to see more EVs be designed with this option in mind. I’d also like to see the propane cylinder option explored.

Categories: BMW, Chevrolet, General, Tesla


Leave a Reply

63 Comments on "Op-Ed: How to Solve the 1% Problem"

newest oldest most voted

Propane cylinders cost $15 to refill at the nearby hardware store. Sounds expensive for 0.74 gallons of gas.

I am spoiled and plan to never return to an ICE vehicle. This includes range extenders. Why? Maintenance. That’s one reason I got an EV in the first place. That being said, I purchased my wife a new ICE vehicle. This way, if we do need to drive that 1%, we can take her car. I don’t have as much of a problem with ICE maintenance on one vehicle, but would rather avoid it on two.

Re: Why? Maintenance.
So I’ve changed the oil in my Volt once in 2 years. And I only did this because of the 2 year mark as the life expectancy indicator showed 50%. I drive in the mode with max regen so I use my brakes only to come to a complete stop. Brake pads are still “new”.

It’s not .74 gallons of gasoline equivalent (GGE). The calculations in the article are wrong. It’s actually 4.72 GGE, which would give an REX an additional 140 miles of range. See my post in reply to Jay below for my calculations.

You should have bought your wife a Volt !

Great piece David!

The i3 does fill a new slot in drivetrain type with their optional range extender. I think Tesla’s has the best technical solution, with large packs and fast charging, but it obviously isn’t economical at this point.

The propane tanks are an interesting idea, but it doesn’t enable long distance travel. It would only be a stopgap until there is sufficient DCQC infrastructure.

I too would like my EV to be able to do the Houston to Austin trip, as I am doing this weekend, but the LEAF won’t cut it. Even if the DCQCs were there it wouldn’t be worth the 2 – 3 stops for a trip that short. We will be sticking with the wife’s ICE on these trips for now.

I believe that the Volt only allows you to use something like 50% of the battery (not sure of the exact number), which extends the life of the battery. The LEAF also doesn’t allow you to use 100%, I believe (but I’m pretty sure it’s more than the Volt). So you’re actually getting less EV range not more. But the battery should last longer.

As an example, the Volt battery is the same capacity as the i-MiEV, but it has a much shorter EV-range. Partly due to the greater weight, but partly because you’re only using half the battery.

Volt uses ~65% so about ~22% to ~87%. I’m still getting 45 EV battery miles in the summer after 2.5 yrs.

The Volt uses ~10.3kWh out of 16.5kWh.

OK, i was speaking from personal experience with my 2013. (now i’m wondering why my Volt isn’t using that last 0.5kWh)

tpyo… (0.5kWh)

MOD EDIT: fixed

I believe the 10.8kwh figure is rather optimistic.

There’s also been quite a bit of discussion on gm-volt.com about how the energy usage figures displayed on the center stack are just approximations and can’t be relied on for very precise measurements. So it has to be taken with a grain of salt.

I typically get a displayed usage of 10.5kwh on my 2013.

That’s DATED information… My late 2013 Volt: 12.9 kWh out of 16 is available for propulsion – that’s over 80% of the battery.
I have charged my Volt several time from full depletion, and the electricity required to return it to 100% charged has always been well above 12 kWhs, as reported to me by OnStar (they report to energy drawn by the car).

No. You’re conflating the amount of energy available FROM the battery with how much it requires to recharge the battery. The previously posted numbers of 10.3kwh (2011 – early/mid 2012) and 10.8kwh (late 2012 – 2013) are correct.

When recharging there are losses. That’s why you see numbers over 12 kwh.

Exactly. Typically EV charging efficiency is about 80%. Thus, to restore 10.3kWh to the Volt battery, you should expect to pay for nearly 13 kWh “from the wall”:

10.3 kWh / 0.8 = ~12.8 kWh

Batteries and charging systems get hot during charging. In this example, about 2.5 kWh is turned into heat.

Good insights on the uses for range extenders. I’m still not sure if I’d want one though, but something to think about

@Aaron: a second EV with REX would have been ideal then?

EV RANGE: advantage BMW i3 (I wish my Volt had a 90mile AER, simply because I only get 25 miles in the winter. Also, I could drive to cities/airports that are 90 miles from me w/out using gas, and charge upon arrival. During my daily routine though, i’m almost 100% EV (up to 200mpg lifetime again))

RANGE EXTENDER: advantage Volt. The BMW i3 has a 25kW range extender that will work for ~80% of situations, IMO. In fact, I think that is probably what Frank Weber told those guys when he went over there. ‘Design a RE that will suffice for 80% of driving conditions, no more, no less’. And the RE is ONLY needed if you go beyond the 90mile AER. I think a trip to grandma’s, 200 miles away, is do-able, as long as its not too hilly.

We really need a bunch of real world data/experiences on the i3 in RE mode.

I completely agree, especially regarding the range extender. You may have even understated the advantage. The Volt has a much more powerful range extender, so in all but the craziest conditions (e.g. driving 90 mph up pike’s peak), you get no hit to performance. The i3 has a much smaller (although presumably more efficient) range extender, sized only big enough to sustain 75-80mph on level ground. You definitely take a huge hit to performance in this mode.

Then there is the gas tank. The Volt’s combined range is ~350 miles. You refuel, and get another ~300 miles. The i3’s combined range is ~200 miles. You refuel and get another ~100 miles. That means for a trip of, say, 250 miles, the Volt can make it in one shot, but the i3 has to stop for gas. Increase that to 450 miles and the Volt has to stop once for gas but the i3 has to stop three times.

I think there could be a misunderstanding about the operation of the REx. It’s common to see this being raised, and not surprising. That said, driving an EV in urban environments typically requires much less than 25 kW of instantaneous power. If your idea of urban driving is barreling down the 405 at 75 mph all the time, then yes, this power level will be required. But even then, there will be moments where the traffic is congested or you are going down a hill. This is when the REx could charge up the battery to ensure that it had enough SOC to help offset high instantaneous demand on the next hill climb. The point is that when you look at two hours worth of urban driving, the total energy consumption will be almost always less than 50 kWh, sometimes even dramatically less. This is the energy the little scooter engine, which has been derated from 60 to 34 hp, can supply. The key here is that the battery and the REx must be allowed to complement each other, and operate in a blended mode, unlike what we have been accustomed to with the Volt. Yes, there are limits to… Read more »

That’s all well and good, but why are you assuming that this car never leaves the city? Isn’t the occasional long-distance highway drive exactly the 1% this article is talking about?

OK, I didn’t mean to imply that. I think you can certainly drive the car outside of city limits. To be clear, I copied the comment from MNL, where I wrote it in response to someone else, and rehashed it a bit. That said, I hope we can agree that the car is designed to operate primarily as a city runabout, and a small REx makes a lot of sense in that context. When you look at the LA, NYC, SF Bay Area, Seattle or even the Dallas/Ft. Worth metro areas, it’s easy to put well over 100 miles of driving per day. I think that’s what the 1% would likely consist of. Personally, I would not hesitate to drive the car from SF to LA either, but if I needed to do that trip every week, I would look for a different solution. Which leads me to this: if one needs to cross the country or go on vacation in the Rocky Mountains, it might be better to drive another car or consider flying. Why am I saying that? Because charging opportunities will be limited on a cross-country trip, and the likelihood of 100% freeway driving is much higher.… Read more »

Great article. In general the existing EV owners don’t like the i3 as they always find ways to make their choice superior. I think it looks OK in the right color. Seems like some great engineering for those that have watch the videos on it from the past several months.

The one point about long distance driving those and multiple DC/QuickCharges is that the car has to be designed for it (liquid cooled battery). The LEAF is not (air). The faster than promised degrading battery capacity problem is exasperated by DC/QuickCharging as it “overheats”/degrades the battery even quicker.

Yup the i3 is cool — but I disagree with everything else you wrote.

I own a Leaf yet would love an i3; it looks pretty slick and must be a total blast to drive. I must say I’d miss that 5th seat and quick-charging though.

Speaking of which: a Leaf driver/journalist you might recognize, Nikki Gordon-Bloomfield, observed battery temperature before and after she performed no less than FIVE consecutive quick-charges.
Not only the car was fine with that, but each one only contributed about 4°C — not exactly something which in my opinion warrants burdening that EV with the cost and weight of a liquid battery cooling system just yet.

You might note that the same design decision was made on the currently only other quick-charge-capable EV besides the Model S, the Mitsubishi i-MiEV.

To the best of my knowledge (but I didn’t manage to find a source confirming this),the BYD e6 battery is also passively cooled, yet is said to be very durable even when routinely quick-charged.

At 32k and 19kmiles respectively, neither Nikki nor myself noted any degradation in our vehicles’ range or performance either.

The i-MiEV cools its battery pack during quick charging with air cooled by its A/C system if the battery pack warms up too much. This design is superior to pure passive air cooling.


The i3 is designed to have DCQC, but might not be on the car from Day 1. (Or ever in the US, if they don’t build out SAE units)

Also DCQCing the LEAF pack definitely causes increased heat. It may not be giving Nikki problems in the UK, but in Houston I have only seen 8 bars of battery temp after a DCQC.

I love the LEAF, but in my opinion the passive air thermal management is not a good design for hot climates. I am at 35k miles and lost my 4th capacity bar this month. More on that later…

@alohart, Josh, John: Wow, thanks for the replies guys. Sorry that my comment didn’t include enough context: I was only responding to scottf200’s preconceptions, in particular that passive/air cooling precludes quick-charging. Hot climates (possibly combined with unfortunate habits like parking outside during the day and in a hot garage at night) expose the battery to high temperatures for dramatically longer periods than quick-charging would; no question that this can be an issue. @alohart, yes, the i-MiEV can actively cool its battery under certain conditions; my point to scottf was, it’s air-cooled, and it doesn’t melt even though the strain put on it during a QC is the highest of any production EV: 50kW on a 16kW*h pack, or over 3C. @Josh: ouch, indeed, Houston we have a problem… Nissan will have to fix that under its new warranty, but I trust you’d much rather not have to benefit from it in the first place… Re quick-charging on the i3: as I don’t see any company volunteering to deploy SAE CCS (understandably; making money on CHAdeMO already isn’t trivial), whether or when BMW provides the option doesn’t matter. Rather save a little $$ and put those on the REx, at least… Read more »

> At 32k and 19kmiles respectively, neither Nikki nor myself noted any degradation in our vehicles’ range or performance either.

Of course you aren’t going to see a problem if you live in a place that has an ideal climate for the Leaf. However, that isn’t the case for vehicles in the Southern and Southwest U.S., and some places in the West (many places in California).

light aero vehicle with blitz charge.
something like this is very possible

Nice article and summery of where we are in the EV market today. Hopefully in the future better refueling infrastructure (electric, propane, hydrogen…) will simplify this decision process. I purchased the Tesla because it was more range than we need 99% of the time. The 1% when we travel it an adventure. I like planning it out and finding solutions on the road. (Ya, I’m a little weird) This weekend we are driving to the top of mt. Washington in NH over 350+ miles round trip. I can do this by adding Storyland (theampark) to our itinerary. Next to Storyland is an RV park with a nema 14-50 outlet and while the kids enjoy the park the car will get a full recharge. Finding these kind of solution is fun.

BMW has tackled range anxiety in some very practical ways. The gas loaner is a great solution. I hope other 100 mile range EV get a gas loaner bundled into the deal to drive more EV sales.

Thanks for the write up

” I like planning it out and finding solutions on the road. (Ya, I’m a little weird)”

LOL. I do this and I don’t even have a Tesla. I look at the supercharger map and try to figure out how to get my imaginary Tesla to various locations.

Great thinking!

All around nice article David. I love my Volt but am intrigued by all EVs entering the market. The i3 has covered a lot of ground by offering with or without the extender, offering double the EV range with a smaller extender. I don’t mind inferior performance with the extender but not sure I want to settle for an extender with a limited range. I do like the i3 offered with or without. I like the Model S offered with different battery options. I enjoyed your take on the gas cylinder. Range extenders are certainly going to evolve. I hope they go the way of the i3 as an option, and I hope future EVs offer different size batteries as an option.

OH VEY! Where do I start?

You can’t put an LP tank in an ENCLOSED SPACE such as a hatchback of frunk and leave it their, especially in hot weather. These tanks vent propane gas from their pressure release valve when they get hot and the LP starts vaporizing. On a hot summer day, a car with an LP tank in the hatch or frunk would violently explode, destroying the car and killing or maiming anyone nearby. In fact, this happens quite frequently in the United States. People exchange their empty LP tank for a full one, and leave the tanks in the trunks of their cars on a hot summer day to go shopping or run some errands. When they come back to the car the interior is filled with propane gas, which explodes when the person opens the door and the dome ignites the propane gas.

Your calculations are also completely wrong. Propane is sold by weight (pounds), not volume (gallons).

Next time do a little research before you blog about a subject you know absolutely nothing about. Google is your friend!

Good points on how throwing a cylinder in the back is dangerous and the article might need to reflect that. The point that I took away was not the simple modification, but simply stating the future of extenders are going to change and that the author was throwing out a wild idea to challenge people to think. I actually would like a little more imagination in this area. I believe this to have been the writers intent.

InsideEvs still hasn’t updated the article to reflect how dangerous it’s is to modify a vehicle to run on propane, which is truly irresponsible. Here is an example of what can happen when a third party converts a Prius to run on LPG.


Why are you worried about the 1% (i.e., using even a tiny amount of gas)? The 20 mile range CMAX PHEV is proving 60% of miles driven are electric, and that’s great! The 40 mile range Volt is proving 75%, and the i3 will likely do much better still. These are all to the good, and the perfect should not be the enemy of the good. Doubtless battery technology will continue to improve, and as it does then more and more electric miles will be driven.

Look at the big picture: there are literally over a billion vehicles in the world. There are about 100,000 plug-ins in the world. So, thus far, we’ve got about 1% of 1% of the market. I’d say there’s room to grow in several sectors.

My Leaf was great. Now, my RAV4 EV is greater. Doubtless my next EV will be greater still. Things are moving in the right direction. I trust that by the time we get to that last 1%, it won’t seem so urgent.

I do wish the leaf offered this option or at least the option of x3 times a year to borrow a car if you need it for a weekend trip.

Anyone know the stipulations on the car borrowing program that comes with this i3? I dont see much of a need for a range extended if you can just borrow a different ICE car whenever you need to go on a long trip.

Honestly all of these are small hassles and it would be much easier for companies to combine resources and build a charging network like Tesla. I have never bought a luxury car in my life but I am thinking of getting the 35-40k tesla when it comes out because I know their charging network will give me peace of mind (even if the supercharger on the car does cost an additional 2k…which i hope is 1k by the time their next car comes out)

How about renting an ICE (or an EV with REx) for long distance drives?

I do know several people who I have talked to about EV’s and a lot of them do have jobs where they have to drive anywhere from 150 to 300 miles a day to visit businesses to where it was 70% to 50% of their driving. They said they liked the idea of the Chevy Volt more then a regular EV in that they could have both electric and a gas back up. If the Chevy volt makes people feel relaxed about getting into a plug in car I think it’s over all good. And what is odd is that in my area I have seen three or four plug in gas cars but I have never seen a pure EV on the road or in a parking lot in my area. Also these same people I talked to would be open to the idea of there was a 200 to 300 mile EV or a 150 mile EV with supercharger stations and as long as the cars coasted the same as a Chevy Impala. Personally I think we are doing better with EV’s today then five to ten years ago in that we had a debate with several people… Read more »
This is what everyone says to me when I talk about my leaf, that it does not have enough range. A much better solution is to stop worrying about it. I have my ranger and the leaf, and use the ranger for long distance trips (which includes city to city here in california). Aside from a new, strange kind of guilt that comes from burning gas after using an electric car all week, and worries about the ranger not getting enough use (ICE engines don’t like being left idle). My wife does not do enough driving right now to justify getting yet another car. But something cheap like a spark would be perfect for her. If I did spend a lot and get a car with bigger battery packs, I would be using a lot more energy just to haul around that weight. The leaf is perfect for its mission, which is a commuter car. I doubt seriously that even in Japan, it works well as a long distance commute car, given a sudden 30 minute pause to charge. Perhaps it is really used to get back and forth to a “rabbit hutch” apartment in the city and only needs… Read more »

I agree with this. I think the current 80 mile range is a little too short though. If it is bumped up to 100 to 140 miles then an EV should be fine for most people.

Putting in 200+ miles of batteries in an EV just won’t work for most people. Firstly, it makes the cars ridiculously expensive like the Tesla Model S such that very few can afford them. And for those that can afford them, they only use the big battery capacity like 3% of the time.

We need a little bit more battery and a change in thinking. For those rare longer trips, just carshare/borrow/rent a hybrid or conventional gas car.

This is exactly why I bought a RAV4 EV. It has a real 100 mile range. I could have easily bought a lesser vehicle and done every single trip to date. I haven’t actually used the full range except for driving it home from an unnecessarily distant dealer. However, I wanted to be able to do 90% of my weekend trips too. I live in Silicon Valley and doing a round trip to San Francisco cannot be done in a Leaf or Focus without charging in The City. We usually go to SF almost monthly, but coincidentally haven’t since I got the car. We still have our 12 year old “road trip” car for the once or twice a year trip to LA or Tahoe. Anything further than that, we fly.

Anyway, I love the RAV and the final cost after tax and incentives was less than half a Model S 60 with Supercharger Access and Air Suspension.

What I think would be the best approach to this problem would be an engine/generator package that attaches to the rear of the car just like a cargo carrier does.

Think a combination of this: http://upload.wikimedia.org/wikipedia/commons/9/9d/Acp_tzero_DSC00467.jpg and this: http://www.pickupspecialties.com/Lund/lund_cargo_net_tie_down.jpg

The obvious concern would be safety in a rear-end collision. But if that could be mitigated, then..

1. You wouldn’t have to make any compromises for storage space to accommodate an engine, generator, fuel tank, exhaust, etc. components on-board.
2. You wouldn’t have to lug around all the extra weight 100% of the time if you were only going to use it occasionally.
3. You could accommodate a larger, more powerful engine without the aforementioned space/weight drawbacks (assuming the vehicle structure is designed for a heavier engine/generator).

I envision a package that could easily and quickly be attached to the car at a dealer or a rental facility using a small dolly/jack. When you need to drive cross-country, you just reserve one of these things and go pick it up and have it installed before you leave town.

Not sure I get the whole conversation here. I have a 2012 Volt and on a daily usage I use the entire range of battery and use the ICE genrator for the remainging miles. My daily work route is 45 miles. With the AC/Heat on I usally use five miles or less on the ICE. So my fillups are any where from monthly to bi-monthly depending on how much weekend driving is done. I am still over 85% EV at this time and never think about the range of the battery. If the battery was larger I would use the ICE less but my attitude about no worries from an energy perspective and if I want to drive to grandma’s house 500 miles away,does not change. The big issue with the Vvolt is the missing fifth seat, and the stupid touch controls on the center console. Other than that I have had zero defects and zero issues, just buy an EV that suits your needs and enjoy not buying GAS!

Hi, I have a Suzuki Grand Vitara with build propane system. First the propane tank isn’t like those from the supermarket. It’s special designed with a few safety features on it, so you can’t just take the empty out and put a full one. Here in Bulgaria we fill up propane on the gas stations just like filling up a gasoline. But as I know in the US you don’t have propane pumps on the gas stations. And as I sad using a grill propane tank from the supermarket isn’t a good idea. In hot summer days on a direct sunlight the tank is getting so hot that I barely hold my hand on it.

Second the reason to use propane is because it’s 0.6 euro/litre, gasoline(petrol) is 1.4 Euro/litre, diesel is even more expensive. I don’t know how much is it in the other parts of the world, but if I have EV and use range extender for just 10-15% of my kilometers traveled probably I won’t save much money or CO2.

Third propane is made of oil (LPG-liguid petrolium gas), so it won’t solve the problem with the oil dependence from the arabbians and russians.

If some EV drivers are allergic to an ICE based range extender, I think they should consider the Thermophotovoltaics alternative that was explored by the Western Washington University team of the Viking 29. Frankly, this TPV system is quiet and was probably not given all the media attention it deserves as a potential range extender. By the way it works with propane gas as well, which fits what you mentioned David.
For my own I would be more than happy with a Wankel based range extender but one that runs on wet bioethanol, so I can even do my 1 % remaining fuel from the left over fruits in the garden.

Here is a link to the TPV powered Viking 29:

Further TPV improvement looks on its way according to this paper:


Great suggestion. I was skeptical at first, but the professional-looking website really won me over.

Who in their right mind wouldn’t want a range extender that works by burning natural gas to a temperature of 2700F — so hot that it glows so brightly that it can then be used to power solar panels and generate electricity to charge the battery? Seems like a no-brainer to me!


I’m just going to say it, because it’s just what I believe: swappable batteries are going to make this all moot. I used to think (circa 2005) it was 50 years away, then 20, now maybe 10, what with technology changing so quickly. But, as Gavin presciently (presceintiously?) stated “Its going to happen whether you like it or not!” And Elon says it can happen in 90 seconds.

So that obviates the need for any chargers outside your home, or wherever you park your EV overnight )lots of assumptions here).

And by the way, how are ER vehicles dealt with in the states that are taxing EVs to make up for gas tax losses? Would they be double-taxed (at the pump and EV tax)?

Here my regular approach when discussing the subject: if you have two or more cars in your household (there are about 80,000,000 such in the U.S.), have one BEV and perhaps one PHEV; if you have one car in your household, have a PHEV. Obviously more electric range on the PHEV is better, but since about 85% of cars travel fewer than 40 miles a day, all PHEVs dramatically reduce gas consumption. For my own example, we have a BEV and a van — nobody makes a van PHEV — and we average about 15,000 miles/year on the BEV and about 5,000 miles/year on the van (which I’ll note in our case are mostly long-distance trip miles where even having a PHEV would not actually reduce gas miles that much).

Interesting analysis, but you blew it at the end there with the tinfoil-hat reference to using propane tanks to extend range. As you see from the comments above, all that did was distract people from the otherwise interesting analysis that preceded it.

Fracking and lovin it!

Gas is wonderful, convenient and I do not have to go through the fuel, range, gymnastics that you constantly encounter. No worries with gas. Oh, and your electricity is generated by solar panels I assume? of course. Gas! it’s whats for dinner! lol

I like both the Volt design and the BMW designs. They should suit a lot of people’s needs. A lot of individuals will get a larger and larger percent of their miles from electricity with these cars. But the other thing to consider is the benefits of even smaller and even cheaper batteries in lower priced cars. The math works like this. If 1000 people run on 25% electricity, they would run 250% more miles on electricity than 101 people driving 99% of their miles on electricity. More cheaper cars with cheaper batteries on the roads would save more gas than a few “perfect” EV’s that get more people to 99%. I don’t think there can be such a thing as the perfect EV/PHEV battery size for right now. We need all kinds of shapes and sizes and prices and features. Just like there are currently thousands of different gas car drivetrain options out there for current gas car owners. different strokes for different folks. For example, I’m not sure Tesla Model S buyers are paying all that much extra just for the longer range. The performance advantage with the larger battery packs are also a huge motivator. Just putting… Read more »

I use my converted Prius-07 plugin every day in electric mode with a 30 miles range.
I have solar panels on my roof and I fill the tank of my Prius every second month or so with 10 gallons, before it was almost once a week.

Sure it happens that I take a longer trip with my Prius, to but more often I will go by air och train and rent a car on those rare trips.
Why not make simple, why put so much effort and money in a car with extended range that most people will use a few times in it’s lifetime.
Think outside of the box, is my best advice.

I still don’t understand what the idea is – here in Europe a Chevy Volt / Opel Ampera costs about € 42.000. For 21.000 you can get a well equipped VW diesel sedan which needs 3.8 litres / 100 km equivalent to 61 mpg. Plus all the pollution from the battery production process is avoided. Mantenance is once a year or every two years – I change my tires from winter to summer more often.


look for the octavia diesel