MIT Technology Review Explains Why the BMW i3 is Not a Purpose-Built, Dedicated Electric Vehicle


This MIT Technology Review article recently caught our eye.  It’s a well thought out piece that attempts to explain why the BMW i3 ended up as a compromised electric vehicle or a purpose-built, dedicated plug-in hybrid.

Wasted Space Filled With Tiny Engine

Wasted Space Filled With Tiny Engine

Though we didn’t initially see the i3 in this light, MIT Technology Review opened our eyes.

Here’s an excerpt from the article:

“In the last few weeks BMW has made a lot of the claim that its new i3, an electric car it will start selling in the fall, is a purpose-built electric vehicle. Unlike the electric cars made by many other automakers, it isn’t just a gas-powered car with the engine and fuel tank swapped for an electric motor and battery back. It’s a new design, with the battery pack and motor kept in mind from the beginning. And engineers went to great lengths to lighten the car to extend its battery range.”

Okay, so it’s a purpose-built electric vehicle?  No, says MIT Technology Review:

“But the i3 isn’t really a purpose-built electric car. It’s a purpose-built plug-in hybrid. BMW designed it so that at the back of the car, between the rear wheels, there’s a compartment for a gas-powered generator (originally designed for scooters) which can recharge the battery as you drive. In the battery-only version, that space is wasted. In a purpose built battery-only electric car, it could have been used for more batteries or more space for luggage.”

Dedicated Extended-Range Electric?

Dedicated Extended-Range Electric?

Ahh…now it’s starting to make sense.  If the BMW i3 was purpose-built as a pure electric vehicle it could either have more range, a larger more powerful motor or additional storage under the rear load floor.  It doesn’t have any of that though.

What it does have is a spot for that optional REx.  For those getting the pure electric i3, there’s wasted space.  Some may feel they’ve been cheated.  But for those opting for REx, you’ll be getting a space-optimized machine that was built from day one to always house that 650-cc range extending engine.

So, the i3 is indeed a purpose built range-extended electric (or plug-in hybrid as MIT Technology Review says) and it is not a dedicated BEV.  It’s been compromised in more ways than one and no dedicated pure electric would be hindered in such a way.

There's No Wasted Space in This Design

There’s No Wasted Space in This Design

Why did BMW decide to do it this way?  MIT Technology Review explains the decision like this:

“The difference matters because of what it tells us about batteries. With its design choices, BMW is basically saying that battery technology isn’t good enough yet. It doesn’t buy the argument of other automakers (save Tesla) that a range of about 100 miles is enough to attract large numbers of customers. BMW, which expects most customers will buy the version of the i3 with a gas generator, is essentially saying the same thing as GM, which builds the gasoline-enhanced Volt, although BMW is using a much smaller engine and gas tank. Customers are going to want more range than batteries alone can affordably provide.”

Again we see this mention that Tesla can do it, but nobody else will even try. Why is it that Tesla has no competitors and that the would-be or could-be competition keeps backing down?

Source: MIT Technology Review

Categories: BMW

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55 Comments on "MIT Technology Review Explains Why the BMW i3 is Not a Purpose-Built, Dedicated Electric Vehicle"

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Wait . . . what? The engine space in the battery-only version is completely wasted? That *is* really stupid. It should be made into luggage space and/or there should be an option to put in more batteries thus increase the range.

I’d like to see a proposed-structurally equivalent- design for this luggage tub MIT TR proposes. Then, once that design is on the table, we’ll talk about waste.

You miss completely missed the point. The point is that they designed plug-in hybrid, not an electric car. That is why the space is wasted when there is no ICE in there.

Actually, the empty space is for the efficient heat pump option for the non-REx i3. It is not wasted.

So it is wasted space if they don’t get that option then.

Isn’t all that expansive room inside also wasted space? So if you don’t drive it with all four passengers, that’s wasted space too? Let’s not start pulling teeth here.

MIT is technically correct yes, but but who really cares. Murderers don’t get off on a technicality, except in the movies. 😉

Proves the point. The engine heats the cabin so it’s a hybrid city car by design and the heat pump is a retro fit.

The Range Extender engine does NOT provide cabin heat.

An i3 with the REx option uses the standard electric resistance heater.

The main BMW is not offering the heat pump on the REx cars because it isn’t needed. They don’t think customers will want to pay for the few extra miles on battery when they already have a range extender.

The i3 is Purpose Built, for exactly what BMW intended. Just not what MIT wants.

What’s considered ‘wasted space’ by MIT is ‘weightless’ space, that could be used for more battery capacity down the road. Building out that space for more storage, would add more weight in itself and decrease range.

“Why is it that Tesla has no competitors and that the would-be or could-be competition keeps backing down?”

Because the $80k 200+ mile Full EV, as a second vehicle, market is a small one at about 11k YTD and shrinking each month since April.

But the $25 – $40k, 20 to 100EV mile market is over 3 times the market at 36k YTD, and is growing at a steady pace.

Right now the primary growth market is in longer range plug-in hybrids as an only car.

– More EV range than necessary on a daily basis
– The ability to drive up to 600 miles in 40+ mpg hybrid mode
– No need to look for a plug away from home on a daily basis
– No maintenance costs to maintain a second vehicle
– No additional cost to insure a second vehicle

The best of both worlds.

I couldn’t have said it better myself. It was purpose built for exactly what kind of car it was planned to be. They make it sound like they took a regular gas car and converted it or something.

No, they explicitly stated that BMW did NOT do that. They are simply pointing out the fact that the i3 was never meant to be a pure electric vehicle, with one of the key points of evidence being the fact that the space for the REx is wasted in the EV version.

Wonder how long it will take before someone stuffs an auxiliary battery in there.

@Bloggin, allow me to correct a few arguments you make with the facts. Tesla S: it’s not an $80k car, but $70k *before* Federal/state subsidies Also, the S’s exceeding 10k sales YTD, which you pooh-pooh at, has both blown any analyst predictions pre-2013 out of the water – and more importantly, the Tesla S is the only, and the *first* ever, EV or PHEV to actually lead the overall (ICE *and* EV) market segment for which it was designed. The S is right now the best-selling luxury sedan in the US, period. More generally, as to BEV vs. PHEV/EREV market potential: Conventional wisdom has beaten this horse of an argument (that only PHEV/EREV are more viable in the mass market) to death so many times, it’s rather illuminating that no one making the argument ever bothers to check reality. The reality is, most BEVs right now are in a demand-exceeds-supply situation: – Tesla S – Nissan Leaf (~30 day inventory, which given their nationwide deployment is nothing) – 500e, as a story on this site just said – Fit EV, and I suspect also the Spark EV is supply-constrained or will be very soon. By contrast, the Chevy Volt production… Read more »

The compliance EV’s you listed offer a fun alternative to the Leaf, for Californians, and to a certain extent other CARB states. They can get their tax credits and have an interesting choice as a commuter car they can put their car pool land stickers on. As a commuter, they don’t need the extra space the Leaf has and they can get something more fun to drive (not criticizing the Leaf, but I’ve driven both the 500e and the Spark EV and they are a blast! However, I wouldn’t be able to own them without also having something else with a little more space and the ability to take a road trip in.

How much money do you think they are making with their $199/month leases? Enough to also sell across the midwest and in Alaska? There is only so much you can read into Fit EV, 500e and Spark sales.

>>>> How much money do you think they are making with their $199/month leases? <<<<<

Enough to put $7500 of federal tax credit in their bank account PER CAR, plus 2.5 credits per "100 mile" ZEV with "fast" recharging that they can potentially sell for many thousands of additional dollars, PLUS fully comply with CARB-ZEV so they can sell beau coup profitable oil burning cars.

They would *almost* make them free to the consumer.

Their leasing company may take the $7500 credit, but that is not profit. The bottom line is the difference between the cap cost and the residual is very slim and it could be a $7500 loss (or more) without it. If they thought it would be profitable, they’d make way more and go nationwide. Chrysler has no plans for this with the 500e. Toyota doesn’t with the Rav4 EV. Honda doesn’t with the Fit EV. GM is a maybe with the Spark.

Yes, they can fully comply with CARB-ZEV, and they cost of making their X number of cars instead of buying credits from Tesla. That’s the point of some of these cars at this point in time. If they weren’t comparing the cost of not complying you really think we’d have the 500e at that price?

“I wouldn’t be able to own them without also having something else with a little more space and the ability to take a road trip in.”

ZIPcar or car rental works pretty well.

I’ve tried that, didn’t work so well for my family. To each there own.

At least in the Portland area, Nissan has has done a hell of a lot better job marketing the Leaf than Chevy has for the Volt. The Volt has sold more overall nationwide, but Nissan has come on strong especially after there (smart) MSRP drop. Regardless, there is NO shortage of either car though. Currently there are 125 Nissan Leaf’s available within 30 miles of my zip code, and 38 Chevy Volts.

As for the Model S, for a car starting in the low $60,000 before credits, how many a year do you think they could sell if they had no (real or artificial) supply constraints? I think they are smart to expand to some overseas markets like they have and generate some buzz elsewhere, when they could have sold here in the states. Keep people waiting, keep the excitement and exclusivity high. I’m honestly not sure how big this demographic is. The people I know with them so far have a higher pay grade than me, and I’m doing alright, thanks:)

“The reality is, most BEVs right now are in a demand-exceeds-supply situation”. That is not really true. The 500e and Fit EV are limited because the are intentionally only making a few as ‘compliance cars’. The Leaf factory can pump out more cars should the demand warrant it. The Model S is barely supply limited and the wait times are down to 30 days by what I’ve heard. I suspect that it won’t be supply limited for much longer as finding customers becomes more difficult.

Yep, you’re exactly right.

Also, the Leaf is now steadily outselling the Volt.

My big concern with EREVs is far more is squeezed into a small space that can go wrong. When it does break down, which will happen much sooner than clean running magnetic induction running EVs, it’ll be much more expensive to get repaired. I’m sure GM is taking that thought to the bank. 😉

“Because the $80k 200+ mile Full EV, as a second vehicle, market is a small one at about 11k YTD and shrinking each month since April. ”

Apparently you don’t understand the concepts of pent up demand, waiting list etc.

Second car? For some, yes. For others, Tesla owners only have Teslas…no gas at all. When GenIII comes out, I will be trading in my hybrid for the Tesla, and I’m a single-car household. 200+ miles is awesome, and perfectly sufficient for 99.999% of my yearly driving. For that last amount, the supercharger network will be perfect. I stop every 1 to 1.5 hours on a long drive, anyway, so the supercharger is not an inconvenience to me whatsoever.

It looks like the supercharger network meets my road trip needs as long as I only want to drive in between Vancouver and Portland. I like to make trips to Montana (Glacier, Yelowstone, & Sealy Lake), Central Oregon, and the Southern Oregon coast. I’d be waiting until 2015 until that ever worked out.

The poor midwest only has one in Illinois.

0 in the Rocky mountain states.

Only 2 in the south, in the southern end of Florida.

This is false advertising to call it a network at this point.

This is a bullshit argument. So lame.
Obviously the car was designed to accommodate two drivetrain configs. To say it’s not purpose built because of that is moronic.

This car has many other shortcomings way before this bs argument

You are an angry, angry man.

Some truth to that. But it is righteous indignation and quite subdued. The wrath that the situation I see so clearly deserves would light the world ablaze.

Wrong Dan. If it was really designed to be BOTH then the would have figured out a better way such that the area used by the engine would have another purpose when the car is sold as a pure EV. But the engine area is a complete waste in the EV configuration. Nothing but a big strut in an empty hole.

BMW just has ICE on the brain and didn’t give the EV version much thought. “We’ll just take out the ICE for those that don’t want it.” They have already said that they expect most buyers to buy with the ICE.

Read my reply above. The space is not wasted.

It is a purpose built BEVx.


I do question CARB’s classification of the BEVx as “pure electric” instead of a PHEV.

I also question the practicality of gas range less than EV range (definition of BEVx). I would rather just have a little more EV range plus DC fast charging than a 35 HP piston engine with a two gallon fuel tank.


So kind of what I have been saying all along re: i3 is that it’s not a great BEV and not a great PHEV/EREV. So what is it? I think it fills a niche in Europe for their small villages, towns – distances between places, and their high congestion, no Co2 zones. Here? Not so much at all. For the USA the i3 really slots in somewhere between a Volt and a LEAF – but for $50,000*. I love all the carbon-composite and great aluminum substructure – but would I pay for it. Why? What I want is a LONG RANGER EV, and to me that means at least 200-300 miles AER. To me i3 and i8 answer all the wrong questions. They’re already boasting they expect high sales in the USA, but I think this is going to make the record books for BMW’s biggest flop ever. The foggy void betwixt Volt and LEAF say – is at this point, either a Volt that switches to CS mode and gets you 40mpg for the remainder of any length trip – but won’t leave you limited nor stranded for 3 hours for a charge – or a 60kwh Tesla on… Read more »

Ditto. The i3 may be a purpose-build EV or an EV with REx, but the purpose itself is not quite clear.

We too?
Look at us, fancy pants? (Carbon Fiber Reinforced) Plastic car? (Th!nk City anyone?)
GM stole some of our customers with the Volt/Ampera that we desperately want back?
We are better than VW/Audi that are unwilling or unable to even put a plug on their cars?

Both VW, BMW (and Daimler) will be joining the CARB-ZEV compliance game starting in 2015, so yes, “compliance” is part of the equation.

BMW – i3
Daimler – B-Class EV
VW – eGolf

“If BMW saw that juicy void as a challenge to fill – they missed the mark. i3 will take you the 85 miles ( if you have flat terrain, 70 degrees f weather and no headwind. ), then you sit for 3 hours charging. If you want the ReX option, you’ll dish out big coin so you can limp along in the slow lane another 80 miles – AND THEN sit for 3 hours charging.”

If you had an i3 with REx, why would you ever stop and charge for 3 hours unless you had already reached your destination and would be parking for that long anyway? I’m not saying that gas range anxiety that requires you to stop every 50-70 miles for a gallon and a half of fuel is fun either, but seriously, why can’t you run 4 tanks in a row of gas to reach your destination? Also, I don’t think the REx will cause you to “limp along in the slow lane” either unless you’re driving up a big mountain.

BMW, by relying on lightweight and expensive materials, and doing the rex thing, is basically betting on batteries not getting significantly cheaper right away. That’s a risky bet, given what battery prices have done in the last 2 or 3 years. If someone makes the BBB (big battery breakthrough) we’re all having erotic dreams about, BMW is going to be caught with their weight on the wrong foot. They’ll have a car design that’s optimized for the wrong battery price. The good news is they can likely bring out an i3 2.0 that uses that cubby hole for a second (optional?) battery without a complete nuke-and-rework of the car. I would expect that they’ve already done the engineering, specced out the parts, and tested it, and could get it into production pretty fast. But this is just one more stepping stone on our path away fro oil and toward electricity for personal mobility. I know it seems like a fantasy, but I still contend that we’re getting very close to the conceptual tipping point for EVs in the US. Once you can buy, say, a 200 mile/charge compact for $20k, a LOT of people are suddenly going to start looking… Read more »


“Once you can buy, say, a 200 mile/charge compact for $20k…”

From your lips to God’s ears! 🙂

I think anyone waiting for that car is waiting for Godot.

What did BMW do to deserve so much hate for their i3? Every car on the market is a compromise of some sort, and the i3 is no different. It’s designed as a fun to drive city car/commuter, with a true range extender (not a dual powertrain like the Volt). As such it fits a unique slot in the ICE to BEV spectrum. Tesla’s proposal is ahead conceptually, but I am not sure it’s technologically superior. I mean, we all know how hard it was for GM to integrate the two powertrains so seamlessly. Could Tesla have just not bothered and opted to slap a giant battery instead? It’s working for them, but the Model S is a $70K+ car, not a $40K one. Big difference, IMO.

The Volt as a true range extender, with the same performance on gas as electricity, and reasonable gas range for trips.

The i3 only has a limp home mode, with gas range that will be annoying for trips.

200+ mile pure EVs with DC fast charging, like the Tesla Model S, will be the future. If you can swing the payments for the Model S you can drive the future right now.


GSP, I disagree with your unfair characterization of the i3 RE mode. “Range Extender” implies that you merely have a way extend the electrical range with some additional technology (like an ICE). The Volt (to its credit) can do more, with its no compromise dual powertrain. But the i3’s RE mode fulfills the premise. It is more than a limp mode, as it will give the car full performance for about twice the battery range, and THEN will be able to go on for longer, albeit with reduced performance. This is a perfectly valid and sensible concept, that will fits the needs of many (sub)urban commuters.

It’s going to do that with 2 gallons of gas?

I don’t think this article is ‘hating’ the i3 . . . it is just pointing out an untrue statement that BMW made. It is not designed from the ground up as a (pure) electric vehicle, it is designed as a PHEV.

If it is not a purpose built EV, then I guess the super lightweight CFRP and aluminum car at 2650lbs and the very quick 0-60 time of 7 seconds and the fast recharge time of 3 hours at level 2 and 20 minutes dc fast charge and the efficiency of nearly 5 miles per kww were an accident?

The Spark EV can do all that except the L2 charge time (only 3.3kW).

A converted oil car.

That really puts the Spark EV in perspective. Good competition for the i3 at a much lower price.


The heat pump makes sence. If true, both range and % winter loss will be “purposeful” and an improvement over the Volt’s 6,000 watt soaker. Weight will make the character of the two very different. Touring manners will be hard to find @2700lbs.

If the space for the oil burner motorcycle 650cc engine is used for a heat pump when there isn’t a motorcycle engine there, that means that there won’t be a heat pump with the oil engine at the same time.

The people I know with Model S’s and Leaf’s all have 2nd vehicles. Sure, battery prices and ranges are improving the last couple years. I hope this continues because it means better EV’s for less money. If we think that’s all there is we need before we EV’s sell in the same numbers as F150’s and Camry’s do, we are deluded. I hate to say it, but the charging network and charging speed is not at a place yet that I would be comfortable making it my only vehicle. I think a lot of people see EV’s as a possible 2nd car, or they don’t even consider them at all due to the charging situation. Here in Portland, we were one of the first Leaf markets and public charging stations are plentiful. I barely use them, as I can easily charge in my garage and this covers my daily driving 99% of the time. However, if I want to take a trip down to the Southern Oregon coast, or to visit friends in rural MT, I can’t do that without adding some serious time to my trip for charging. Until the charging situation changes, the i3, Volt and even (to… Read more »

Let’s see…we are living in a transitional time when battery technology is in it’s infancy. Oil consumption is being phased out. I commend BMW and ALL the other car manufacturers in designing cars for this transitional time.

LOL! Why offer just the BEV?

Never mind with the BMW badge they will be able to price it twice that of Volt and it will
sell like hot cakes 😉

Just proves VOLT has the correct combination & is still better than an i3 !!!

It is kind of strange to have an MIT article going into such a low dept. PHEV is an insufficient description. They should know that the Volt is exactly a dual motorization vehicle while the BMW i3 is a true REEV. BMW has been placing a standard piston engine in the car for now, but their configuration allow them to evolve to more advanced generators like a FPDG (Free Piston Direct Generator) or a DEFC (Direct Ethanol Fuel Cell) in the future. Not so for the Volt, which require the transmission of a circular motion to the wheels, instead of just electricity generation. In that sense, the i3 is more advanced and does indeed affirm the optimum compromise between EV and range extender, even if it has some flews like a to small 2 gallon tank (actually due to CARB incentive). Now if MIT really stubbornly believe that pure EV is the present optimum, which it is not, the fact of having a void in an EV car doesn’t mean it is not a pure EV car, especially with the Rex miniaturization in mind that should soon reduce that empty space to a mere shoebox size. Beside according to the… Read more »

No competition for tesla is going to be like that until more luxury car makers come out with bigger and better EV cars good as tesla. How did Tesla a new company picked up so good? They named it right as “Tesla” if Tesla was named as some other name would have not sold even half of what they sold now. If Tesla was releasing with EV with range extender they would have not done well either. Nikola Tesla, is what’s promoting Tesla motors for free.

The CA version of the i3 will be a disappointed market. Firstly, release date and obtaining the HOV sticker makes the i3 to market a bit late.
Another big bugbear for the CA market is the “REx”. It can only switch on when the battery pack is low. God help them on the highway. That scooter motor is simply not enough!

However, in the EU Anyone taking an extended trip will turn on the REx early so charging will be more leisurely, (read: efficient) and the cabin will be warmed by the motor.

BMW could of fitted a further 10KWH with no issues whatsoever between the rear wheels. In fact noting the packs spaced out under the floor I’m wondering why that has not been fitted with an extra 15KWH already! It’s a 45KWH car using the wasted space to take a totally unserviceable engine replacing 25KWH of batteries.