2014 BMW i3 Range Extender: Heavier, Less Electric Range, Less Performance

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Electric or range-extended electric?

It's a choice that normally means selecting between entirely different cars, but when the 2014 BMW i3 debuts in the U.S. next Spring customers will be able to choose both options in the same car.

The range-extended option marks out the i3 as a competitor for Chevrolet's Volt, but unlike GM's product, the i3 'REx' will require you to make a few compromises on range and performance.

That's because the 650cc maxi scooter-sourced, twin-cylinder gasoline range extender (quite a mouthful, so let's hope you don't have to explain it to people too often) is really a last resort, rather than a genuine aid to longer-distance driving.

BMW seems to have admitted as much by allowing drivers a free loaner whenever they need to tackle a longer distance, but the clues are in the i3 range-extended model's specification too.

It's a portly old thing for a start. Given BMW's efforts with carbon fiber reinforced plastic and aluminum to reduce the i3's weight to 2,700 lbs, some of that is undone by adding the 330 lb range-extending engine.

The weight is right over the rear tires too, which is great for traction on poor surfaces (as any old VW Bug ad would tell you) but less outstanding for the car's front to rear weight balance, near 50-50 on the regular i3.

2014 BMW i3 Electric Car: Full Details And Images Released

The extra bulk does nothing for performance or all-electric range, either.

BMW's official statistics give the regular i3 a sprightly 0-62 mph time of 7.2 seconds, but the i3 REx adds a further seven tenths to that sprint. Other acceleration metrics are also slower, while all-electric range drops by 10 percent.

Range-extended owners are unlikely to be affected by this too much of course, since overall range increases by 86 miles once the engine kicks in--but it does highlight the effects of the extra weight.

Other differences between the two are more subtle, but may also contribute to the reduced electric range. The first is air resistance--the REx has a drag coefficient of 0.30 to the standard car's 0.29. The next is rolling resistance, as the REx actually features marginally wider rear tires--175/65 R19, to 155/70 R19. Both use the same 155/70 R19 front tires.

Finally, though not unexpectedly, the REx'll cost ya'--at $45,200, the it's $3,850 more than the battery-only i3. You can add BMW's $925 delivery fee to both of these, and both prices are before applicable federal and state incentives.

BMW still expects as much as 80 percent of i3 buyers to choose the confidence-building range-extender, but those able to get away with the electric-only model will get the more efficient car.


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Comments (67)
  1. What is more important: Many States will not allow an income tax credit on gasoline range extenders. Georgia for example does not allow $5000 credit on Volts.

  2. In Georgia then you'll pay nearly $4,000 for the ReX and then loose another $5,000 in credits thats almost a $9,000 loss, whereas pure electric versions will be 9 grand cheaper after state credits.

  3. That is a silly policy. It is good that I left that state.

    No wonder that Leaf is selling well over there. That is almost FREE after all the discount.

  4. Nice thing Texas has no income tax.. Though a break on the sales tax would be nice!

  5. For drivers concerned about the 86 mile range, how about a third option - a bigger battery. This "range extender" looks like a solution only a mother could love.

  6. I agree that a bigger battery is the more elegant solution. However: even the weight of the range extender in extra battery capacity would only add ~16KWh which would get you less extra range than the range extender solution while adding probably double the cost of the range extender.

    It's all about striking a balance.

  7. I tend to agree - Extrapolating from the 18.8kWh/450 lbs/80+ mile range battery, an added 350 pound batterywould be about 14+kWh and add 60+ miles for a total of 140+ miles range.

    I think many would be happy with that, though the extra cost for the larger battery would likely add around $5,800 or so to the OEM COST of the car based on $400/kWh. So, the question is - would you buy a $48,000+ sub-compact (albeit with compact-class interior) that has about 140-150 mile range?

    So, if BMW thinks enough people will spend $46,000+ on the i3 REx with ~160 mile range, why do they not have confidence just as many would buy a long(er) range all-electric i3 for $48,000+?

    Anyone agree or disagree or have more to add?

  8. I think that if BMW is actually paying $400 per kWh, Tesla will truly eat their lunch, and this will be just another compliance car token.

  9. I wouldn't be surprised if BMW's cost are even higher than that. It's speculative of course but I think Tesla's battery solution really puts it miles ahead of the pack in terms of cost and energy density. I wouldn't be surprised if Tesla could have offered BMW a ~40KWH battery solution that would have given the i3 an all electric range of 160 miles at lower cost as BMW's 22KWh battery+range extender solution and have saved about 400LBs in weight in the process.

  10. Yes it's very speculative. And keep in mind that we are talking about costs to the consumer, which is retail price - not BMW's costs.

  11. @Jeff Hre: Some speculative numbers to make this more interesting: Tesla 40KWH battery @ $250/KWh is $10K cost to BMW. BMW: 22KWH battery @ $400/KWh (let's be optimistic)=$8800+ cost of range extender makes let's say a total of $11K?

    BTW my weight saving calculation is off. the 40KWH battery should weigh about 600LBs versus a total weight of 770LBs for BMW's solution.

  12. Some people will want a fully electric BEV, thats the point of getting an EV. Obviously, BMW still lacks the prowess of Tesla when it comes to making mouth-watering EVs..

  13. It's a similar story in NJ afaik and I have a 75-85 mile/day commute so, yes, I'd choose the larger battery option and hope for some DC charging stations.

  14. The loaner won't be free, at least in Canada. It's likely to be included as part of an optional package. So it might not cost you at the time of use, but it will at the time of purchase. They haven't yet said how much.
    As for the REx, if it's so bad, simply don't buy it, and save the $4,000. It's only being made available to appease the nervous.

  15. I hope BMW and others will integrate the light weight Capstone turbine as a range extender or use the Envia batteries so a range extenders may no longer be attractive.

  16. What advantage do the Envia batteries provide? If they are much better, why are they not the choice for most other EVs? I ask not because I mean to be negative but has Envia completely validated results and shown them in production vehicles?

    If Envia batteries are better, great, of course. Can you show anything that shows why you feel the same you do? I'm not that knowledgeable about specific battery makers, so that's why I'm asking.

  17. Envia touts 400Wh/kg, which is roughly 3-4x the density of the BMW battery, though they're still not being manufactured for production vehicles yet AFAIK. Presumably GM, as an investor, will bring them online relatively soon, and hopefully Volt 2.0 will have, say, 40kWh usable along with a more-efficient purpose-built genset.

  18. I just sold my stock in Capstone. I originally thought they had an ideal solution for a REx, but the prices are way too high for automotive application. I don't think they want it badly enough.

    I am definitely watching Envia Systems. If their battery chemistry proves durable enough, it will be a game changer for the industry. Until then, Tesla seems to have the best approach to long-range EVs.

  19. As I understand it, the REx was designed after the i3's design itself had been pretty much completed. That makes it an afterthought, hence the less than optimum result.

  20. You could be right, it wasn't announced from the beginning and that may explain why they had to outsource the engine and why the gas tank is so tiny. If they had given it a bigger tank they could have given it something like 300 miles combined range. It's strange how poor the ReX option is.

  21. Of all the cars to design first, then engineer, I would have picked the i3 last. They didn't have to make this car so ugly. It was like they were trying to validate that an ev needs to look either weird or ugly (and often both) in order to be certified as environmental.

  22. Looking at the pictures it seems strange that BMW decided to drop the window area down for the rear seat. It really distracts from a potentially good design. Without the rear side window drop downs the car would look much better.

  23. I kind of like that detail myself - it makes the profile less plain. What I really do not like about the car is the front end - it's almost certainly the part most people will see (in their rear view mirror) as the car hardly has BMW class performance. And, thought the head on lines are ugly, the worst and most pointless bit is the stupid double kidney shaped grill, which isn't a grill at all. It's just a couple of kidney-shaped outlines to say "BMW" - I think that's really lame and they should just have the BMW badge up front - heck, make it larger (a la VW bus - well, maybe not THAT much) even.

    I honestly feel that BMW completely missed the target. They should have done an electric PERFORMANCE car to best honor their heritage.

  24. I do not have range anxiety so I'm going for the pure electric version, and I'm even happier about that knowing the my i3 will perform better. While I can appreciate the fact that the all electric range won't work for everyone I'm sure there will be a few people who will pay for the ReX simply for comfort sake even though they may never use it. If most Volt owners are able to keep their cars in electric mode for the majority of their work week I don't see why the ReX in an i3 would ever start.

  25. Yep--after finding out more info the range extender on the i3 really makes no logical sense. Since the car is admittedly for commuting only (not for road trips) why would you need the extender? 80-120 miles per day around town would surely be sufficient the majority of the time. It's still sad that this fantastically high tech vehicle is so limited.

  26. @CDspeed - good luck - I am looking forward to posts on your ownership experience.

  27. I've kept track of my daily mileage for the last two years, I'll be fine my daily average is 38 miles. And I'm looking for a convertible as a secondary car.

  28. REx is there to reduce the "oh crap" moment"... It is an insurance. But in this case, a pretty expensive one.

    I think REx is there to make up for the lack of DC charging...

  29. No DC charging?? BMW is this late to the party and they left that out and threw in a hobbled range-extender that only a lawnmower could love?
    I was on the fence about this vehicle but not anymore - it's off the list.

  30. @Morin: The BMW i3 will offer, perhaps as an option or perhaps standard--U.S. specs aren't final yet--the Combined Charge System (CCS) combination charging port. That includes the Level 2 socket with an additional quick charging plug below it.

    There are almost no CCS charging stations today--the CCS standard is where CHAdeMO was in 2009--but they will roll out over the next few years, perhaps at a slower pace.

    But it's incorrect to say that an i3 has "no DC charging".

  31. Even if BMW uses the CCS charging port, there are NO public charging station yet.

    So, in effect, it has "NO DC charging"...

  32. There are more comments in this thread
  33. Let's see; The i3 is $42k and The Leaf is $30k....I think I'm not a buyer yet even with $10k of incentives.

  34. The i3REx (can we call it the "B-Rex??) is a gift on a silver platter to Chevy. With a slight price disadvantage and what has to be poor relative ICE performance, the Volt should look like a pretty good deal to prospective buyers, especially if Volt electric range is increased on future models. Comparisons are inevitable.

  35. Chevy must surely be pleased to see that the Volt still holds its niche as a car which can be used as both a commuter and a road trip car without any difficultly whatsoever. If they are able to increase the EV range in future designs so much the better for them and consumers.

  36. Volt is designed to be a short EV commuter and a long distance hybrid all in one. That is what GM believed from day one in its design goal basd on today's (or back in 2006/2007) battery technology and projected infrastructure.

  37. the design is still very good even today.

  38. It is.

    But I expect that once an affordable sub $30k 200mile BEV is out with fast charging and better infrastructure, the appeal of Volt will be diminished significantly. Of course, the Voltec powertrain can be easily put in a SUV or pickup trucks...

  39. As can the Tesla powertrain ;)


  40. Yes. But the net effective range will be significantly different for a work truck.

    A 85KWh battery won't be able to last while towing a 10,000 lbs load going up the hill...

  41. The Lotus EV Range Extender only weighs 115lbs for 35kwhrs, easily enough for this new sad excuse of an overpriced EV.

    They keep making them overweight, overpriced and butt ugly in too many cases.

    Where are the under 1k lb composite cool EV's that only cost $12-15k?

    Why if this is suppose to be light it weighs 3klbs with gen?

    They could make this in 1800lbs in medium tech composites.

    The GM UltraLite shows the way, just done in medium tech composites instead of CF.

  42. It still amazes me that you don't already make the world's best EVs. Ah, that's right, you think that you already do. There's absolutely nothing that any OEM can do or will ever do that's not inferior to what you claim to already do.

    Hard to believe that with your assured brilliance that a big OEM isn't already paying you millions.

    My favorite ridiculous comment was this. "Where are the under 1k lb composite cool EV's that only cost $12-15k?"

    Well, you tell us. Batteries + electric motors + the CF/composite alone would come close to obliterating that target. Oh, that's right, you're better than every EV maker and OEM in the world, in addition to getting better pricing, too.

  43. Jerry Dycus' other comments aside, he does make a good point about the ReX - it's quite overweight compared to the Lotus one and somewhat underpowered.

  44. Right Jerry. Cutting edge hi-tec in three of the four most expensive, structural areas of the vehicle's most complex systems, advanced leading edge powertrain, low volume to start in a premium category and a 12k price tag. Uh huh, riiiiight?

  45. I was excited about the i3 because it was RWD and electric. Coming from BMW, it had to be awesome, right? Well, no.... limited range, limited power, limited seating and ugly as hell..... swing and a miss. Compliance car, nothing else.

  46. I don't see how you can call this a "compliance" car. BMW has invested heavily in this vehicle and have stated they will make a profit from the sales of the vehicle (something many other EV manufacturers are still struggling with). The carbon fiber body (produced at a plant they own as a subsidiary to ensure supply) does not come cheaply and is incredibly innovative for a small EV. It not only keeps the weight of the vehicle low, it makes it safer as well. Really one of the coolest new features of this EV car IMHO.

    But I agree with you about one thing--they should have worked harder to get increased range--even if it meant going with larger, heavier batteries. Still, I admire their effort with this vehicle.

  47. @George: I would disagree. BMW has said it plans global production of up to 30,000 cars per year. Far from compliance levels--although there's an argument that this *might* be a compliance car in the U.S. only. But it's not one in the sense that we've defined it: one that will only be sold in limited markets for the purpose of meeting CARB ZEV rules. Far from it.

  48. By 30,000 cars, I would assume that BMW will actually make money on the car on a per car basis excluding initial R&D investment.

    That is very interesting considering the price and volume compared to the more "conventional" Leaf and other PHEV.

  49. John, I think that they big tell will be if they sell them through separate i dealers as they did with the MINI. Then we'll know for sure that it's not just a halo car.

    For what it's worth, I think BMW is similar if not a tiny notch higher than Nissan on the 'EV Advocate' scale if there were such a thing. This car's a huge investment in tooling… unless of course dominance of the CF supply business was the purpose of this car… who knows.

  50. @Michael: While MINI is a separate brand, BMW 'i' is a sub-brand. I'm not aware of any plans for BMW to set up a separate dealer network, although like all plug-ins, the early dealers will be a subset of the total who have to be separately qualified, with new equipment, charging stations, mechanics qualified, etc.

  51. Okay, I am surprised to see so many "negative" comment on the i3 with REx. After all, it is good to have more choices among EV community.

    BMW gives you an option. IMHO, I think it is a GREAT option.

    1. It gives you an ultra light, high tech EV with about 80-90 miles Range.
    2. It gives you a BEV with optional REx to reduce range anxiety. Sure, it won't work like the Volt or get the similar MPG as Prius Plugin, but it is really intended for reducing anxiety. If you worry about it, then get it, if you don't, then don't buy it. Choice is great. That REx is designed so you won't worry if you really attempt that 80 miles drive. Most Leaf owners won't attempt a 70-80 miles drive in questionable weather without planning and DC charging.

  52. 3. It is another choice on top of what each plugin car gives you.

    Prius plugin and Accord Plugin: 11 miles electric (sort of), 47-50mpg.
    Ford C-Max Energi/Fusion Energi: 20 miles electric, 41-43MPG
    Volt: 38 miles electric, 37-40mpg
    i3 with REx: 75-85 miles electric (projected), 34-36mpg (projected)

    I firmly believe in choices. It is good for the EV community and the more visibilty the better it is for the market and all the EV buyers.

  53. The EPA mileage for the VOLT is very laughable. My dash shows 250+ mpg/day and 250+ mpg/life time. The worst I have ever seen is 62 mpg on a 238 mile jaunt.

  54. @Richard: Apples and oranges. The EPA is quoting gas mileage for the Volt (37 mpg) in pure range-extending mode, where you're citing BLENDED mileage that combines electric-only miles with gasoline miles. Two separate measurements.

  55. @John: But this article IS about a range extended vehicle, partly. The Volt doesn't have the problems that the REx has. You keep siting the Prius which is using PHEV. The Volt is a PHEV ,,, only a much better one. The EPA for Volt extended is very unrealistic ... get real.

  56. @Richard: I'm utterly not following your logic here. The Prius Plug-In Hybrid is PHEV, and so's the Volt, but the i3 with ReX isn't?

    The point I'm trying to get across is that the EPA rates PHEVs/EREVs in two different modes: Running on gasoline, and running on electricity only. It issues a mpg rating for the gasoline/hybrid mode, and an MPGe rating for the pure electric mode.

    Individual owners will have different use patterns, so their *blended* figures in "MPG" will vary for the Volt from 35 to infinity.

    Are you saying that once the battery is exhausted in your Volt, you get far in excess of 37 mpg in range-extended mode ONLY? I could believe 40 mpg, but it's hard to imagine 62 mpg.

  57. @JV,

    In Volt's extended range mode, 32-46mpg are all possible, depending on the driving mode. In the city with a lot of stop and go and hard acceleration and A/C use, it tends to be worse. At hwy speed with easy cruising low to mid 40s is easily achieved.

  58. I agree with having choices. I was originally going to buy the i3 with the REx. Now, I will probably skip it.

  59. BTW, another fact is that even with all that so called aerodynamic improvement, the drag on the i3 is no better than the rest of the plug in cars. In fact, it is worse than Prius, Civic, Accord and various family sedan.

    The biggest efficiency improvment is coming from narrow tires and significant reduction in weight.

    So, I will be curious to see what its "hwy" range is and what "hwy" efficiency it gets. Maybe BMW is NOT concerned about that since it is clearly "marketed" as a "city car".

  60. Given that BMW has proved what DOT already knew 10 years ago -- most people drive 35 miles an hour a day or less -- I don't really understand this decision-making at all. Why not build the car with a 50-60 mile battery and offer a 1-liter range extender with a 5-ish gallon tank? (Let's leave aside this CARB nonsense and actually live in a world where companies build good products, not regulatory-focused ones.)

    >That< car would be on electricity well over 80% of the time (if we extrapolate from Volt data) and perhaps more for many drivers, but it would actually be able to go 200+ miles when you wanted to.

  61. People opting for the REx likely have the extra money. After driving my Volt for a month I have noticed that even in California you have to go out of your way to find usable charging stations and 1/2 the time those stations are either being used or are being ICE'd. I'm a firm believer in range anxiety. Even with my Volt I end up with a bit of anxiety because I hate using the ICE. For some consumers the idea of never having to sweat finding an open charging station is worth the extra cost of a range extender. Then again, I'd prefer more range like the Tesla than an emergency REx.

  62. Will be interesting to see what the reception for this car will be after the EPA gets through with it.
    ALL of the "numbers" currently provided by BMW for AER and mpg are essentially meaningless as they were based on Euro NEDC test cycles which are "urban" only where the average sped is only 20.8 mph...

  63. BMW didn't inform its future Rex-clients yet what the performance and speed will be AFTER the battery has come down so far that the Rex is needed to generate extra electricity for the extended range.

    In other words: what are the top speed and performance above the 170 km all-electric range?

    Or to state it more scientifically: what would be the top speed and performance on level ground that can be sustained while using the Rex, meaning that it is not draining the battery.

    This is important and it is missing from the information offered by BMW.

  64. B/C BMW doesn't want you to use it. It is NOT an EREV. It is an insurance against "range anxiety" or an emergency onboard tow truck.

    There was a GCR article couple years back that quoted a study in Japan that if people have better infrastructure or onboard REx, the owners will likely to drive "farther" on a per charge basis and will be using more % of the total battery charges...

    So, it is really a range anxiety remover but NOT a daily use or long trip insurance like the Volt.

  65. REx range extender is a good idea. As with anything of this type I'm sure you have options for the REx. In the 1970's there was a lot of snow, so extra weight over the back tires like the VW bug was a fantastic idea. Needing extra weight over the back tires may not be for the near future though. Maybe more of tires popping because of the heat and the hot roads. So less weight may be good. With work done on new technology air batteries a REx made of aluminum air batteries would be around 100 pounds and could be hot swapped out at one of the convenient BMW dealers, in a few seconds, like they swap out ebike batteries in china now. They might consider that. Plus the range would be in the thousands and not 10's.

  66. Can someone please explain to me how REx works? Is it constantly running or kicks in when battery is running low? I'm wondering if there's an option to turn off the gas engine and only use it for longer road trip

  67. @Morok: The range extender only switches on when the battery is discharged. It then generates electric power to run the vehicle, buffered through the battery. It does not run at all until the battery has reached its minimum level of charge.

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