Review: 2015 BMW I3 Range Extender Aka I3 REx (With Video)

Alex L. Dykes
by Alex L. Dykes

Some call it a hybrid, some call it an EV. Some have called it a REx, a BEVx, a landmark vehicle in EV production, and others simply call it ugly. One things is for sure however, the 2015 BMW i3 turns more heads in Northern California than a Tesla Model S. Not since I last drove the Jaguar XKR-S have I received as many questions while parked at the gas pump, or visited a gas pump so frequently, but I digress. In a nutshell, the i3 is technically a hybrid or an EV depending on the version you get.


The “hybrid” i3 isn’t the kind of hybrid you’re used to, this is an all-new classification of car defined by the California Air Resources Board (CARB) as a “Battery Electric Vehicle with Range eXtender” or BEVx. BEVx is the key to understanding why the i3 operates the way that it does and why the Euro version operates differently.

California has decided (for better or worse) that some 22% of cars sold in the state must be zero-emissions vehicles (ZEV) by 2025. While that sounds straightforward, nothing cooked up by the government and lobbyists can ever be easy. Rather than an actual percentage of cars sold, CARB created a credit system where an alphabet soup of classifications (PZEV, AT-PZEV, TZEV, etc) get partial credits and true ZEVs can get multiple credits. Into this complicated world came the unicorn that is the BEVx. Despite having a gasoline burning engine, BEVxs get the same credits as a vehicle with the same range and no dinosaur-burner. The distinction is important and critical. If the BEVx requirements are met, the i3 gets the same 2.5 credits as the i3 EV, if not it would get a fractional credit just like a regular Prius. The requirements are: the fossil fuel range must be less or equal to the EV range, EV range but be at least 80 miles, the battery must deplete to a low level before the generator kicks in and may not be charged above that level. In addition the fossil fuel generator or APU must meet CA’s SULEV emissions standards and have a long battery warranty. There’s one important catch: the carpool stickers. While BMW gets to have the i3 REx treated like an EV for credits, i3 REx owners are treated like hybrid owners for the carpool sticker program. The EV model gets the coveted (and unlimited) white carpool lane stickers, while the REx gets the same quantity-limited green stickers as the Chevy Volt. If CA follows course, the green sticker program will eventually sunset like the yellow-sticker hybrid program did in 2011.


The i3 is about more than just ZEV credits, it’s about putting new materials and processes into production for real drivers to experience with some funky modern style tossed in for good measure. In some ways the i3 is a return to body-on-frame construction, you see this is not a 100% carbon fiber car as some have incorrectly said.

The i3 is composed of two distinct parts. On the bottom is the drive module which is an aluminum chassis that holds the drivetrain, suspension, battery and crash structures. Connected to the drive module is the “life module” which is made of carbon fiber reinforced plastic or CFRP. While obviously a little heavier than a car made entirely out of CFRP, the aluminum crash structure is more easily repaired in the event of a minor collision. The result is an EV that tips the scales about a cupcake shy of a Mazda MX-5 with an automatic transmission (2,634 pounds). Adding the range extender adds just 330 more. That’s about 370lbs lighter than the already impressive 3,000 pound (approximate) curb weight of VW’s new eGolf.


Up front the i3 gets a familiar BMW roundel and a blue interpretation of the signature kidney grill. What’s different about the i3 is that the kidney isn’t used for cooling, even in the range extending version. The biggest departures from BMW norms however are the headlamps which lack the “angel eye” rings BMW has been known for and the high beams that are placed lower in the facia. (No, those are not fog lamps.) Regardless of the trim or paint color you choose, the hood, lower valance, side trim and rear hatch will always be black.

The side view generated the most head turns due to the undulating greenhouse and “pinched” look to the rear windows. I didn’t find the look unattractive, but it does reduce rearward visibility in what is ostensibly a practical city car. Out back the hatch is composed of two sheets of glass, one for the rear windscreen and the other forms the “body” of the hatch and actually covers the tail lamp modules creating a very sleek look. Turn the steering wheel and passers-by will immediately forget about the pinched greenhouse and focus on the tires. Yes, they are as skinny as they look, but the proportion is the real key to the “bicycle wheel” look as one passenger called it. Our tester was shod with 155/70R19 tires up front and 175/70R19 in back. For reference a Toyota Sienna uses a T155 tire as a spare. Thinking critically, there have been plenty of cars with tires this narrow, but I can’t think of a single one where the width combined with a nearly flat wheel that was 19 or 20 inches across.


Freed from the usual front-engine, rear-drive layout of every other BMW, the Germans decided to reinvent the cabin. Because the drive module under the cabin houses the majority of the crash structure, the CFRP body was built without a structural pillar between the front and rear seats. The suicide door design means that getting in and out of the rear seat is surprisingly easy, as long as you haven’t parked too close to another vehicle. Without the transmission tunnel the HVAC system was pushed as far forward as possible allowing the driver and front passenger’s footwell to become merged. (There are just two floor-mats, one up front and one in back.)

The doors aren’t the only unusual thing about the i3’s interior, the design is decidedly Euro-funky. From the steering column mounted shifter to the “floating” iDrive display and glove box on the “top” of the dash rather than the front, the i3 designers went out of their way to think out of the box. The concept-car like theme doesn’t stop at shapes, the materials are a little unusual as well. The upholstery in our model was a wool/recycled-plastic blend fabric and the dashboard and door panels are made from a bioplastic reinforced with kneaf fibers (a kind of jute.) Front seat comfort proved excellent despite lacking adjustable lumbar support. The rear of the i3 was surprisingly accommodating, able to handle six-foot tall folks without issue. Because the dash is so shallow, a rear facing child seat can be positioned behind that six-foot person without issue. As with other small EVs on the market, the i3 is a strict four-seater. My only disappointment inside was the small LCD instrument cluster (shown below) which is notably smaller than the i3’s own infotainment/navigation LCD.

Under the hood of the i3 you’ll find a small storage area (also called a “frunk”) that houses the tire inflater and the 120V EVSE cable. The i3’s frunk is not watertight like you’ll find in the Tesla Model S, so don’t put your tax paperwork inside on your way to the IRS audit in the rain. Cargo capacity behind the rear seats comes in at 11.8 cubes, about the same as your average subcompact hatch. Getting the i3 sans range extender won’t increase your cargo capacity as the area where the range extender fits remains off limits from your luggage.


Being a rear wheel drive electric car, the i3’s motor is located under the cargo floor in the back. With 170 horsepower and 184 lb-ft of torque on tap, the i3 is one of the more powerful EVs on the market. The light curb weight and gearing in the single-speed transmission allow a 6.5 second sprint to 60 in the EV and 7.0 in the REx. Powering all the fun is a 22kWh (18.8 kWh usable) battery pack in the “drive module” coupled to a 7.4kW charger capable of charging the car completely in just over 2.5 hours on AC. Should you need more electrons faster, you can opt for the new SAE DC-Fast-Charge connector capable of getting you from zero to 80% in under 30 minutes. 18.8kWh sounds much smaller than the 37kWh Tesla battery in the Mercedes B-class, but the i3 is much more efficient putting their range figures just 5 miles apart at 80-100 miles for the EV and 70-90 for the REx.

Next to the motor is the optional range extender. It’s a 34 peak horsepower 0.65L 2-cylinder engine derived from one of BMW’s motorcycle powerplants. Permanently to a generator, it can supply power to the motor, or charge the battery until it hits about 6%. The 1.9 US gallon gas tank is capable of powering the small engine for an additional 70-80 miles depending on your driving style. There is no mechanical connection at all between the engine and the wheels. Think of the battery as a ballast tank, you can pull 170 HP out whenever you want, but the supply refilling the ballast flows at a maximum of 34. This means that it is entirely possible to drain the battery and have just 34 HP left to motivate your car.

Sounds like the Volt you say? Yes and no. The Volt is more of a plug-in hybrid with some software tweaks and the i3 is a range extending EV. I know that sounds like splitting hairs but some of this comes down to the way GM decided to market the Volt when it launched. The Volt’s transaxle and 2-motor/generator system is actually much closer to the Ford/Toyota hybrid design than anything else on the market. Because of that design it can operate as an EV, as a serial hybrid or as a parallel hybrid. Interestingly enough however, maximum performance happens in gas-burning mode, just like the plug-in Prius and plug-in Ford Energi products. With the i3 however, performance is always the same (unless the battery is totally dead.) Also in the Volt you can opt to “reserve” your EV capacity for later, and that isn’t allowed in US bound i3 models (you can in Europe) in order to get that coveted BEVx classification.

Technically speaking, it is possible for any hybrid (i3 included) to enter a “limp mode” where the battery is depleted and all you have left is the gasoline engine. The difference is what you have left when this happens. The i3 has far less oomph in this situation than even the 80 HP Volt, 98 HP Prius or 141 HP in the Fusion/C-Max Energi.


The i3’s steering is precise and quick with just 2.5 turns lock-to-lock and the turning circle is 10% smaller than a MINI Cooper at 32-feet. Due to the combination of a fast steering ratio, narrow tires, electric steering assist and the incredibly light curb weight, the i3 can feel twitchy on the road, responding immediately to the slightest steering input. That feeling combined with low rolling resistance tires (that squeal long before they give up grip) make the i3 feel less capable than it actually is. Once you get used to the feeling however, it turns out to be the best handling non-Tesla EV currently made. Is that a low bar? Perhaps, but the i3 leaps over it.

BMW’s “one pedal concept” is the fly in the ointment. Here’s the theory: if you drive like a responsible citizen, you just use the accelerator pedal. Press on the pedal and the car goes. Lift and the car brakes. Lift completely and the i3 engages maximum regenerative braking (brake lights on) and takes you to a complete stop. As long as the road is fairly level, the i3 will remain stopped until you press the go-pedal once more. On paper it sounds novel, in practice it annoyed me and made my leg ache. The reason is that in order to coast you either shift to neutral or hover your foot in the right position. If the i3 could adjust the “foot-off” regen, I’d be happy. Driving the i3 back to back with VW’s new eGolf didn’t make the one-pedal any better because the VW allows you to adjust the regen from zero to maximum in four steps easily and intuitively.

The i3 EV’s wider rear tires mean that despite being RWD and almost perfectly balanced you get predictable understeer as the road starts to curve. You can induce some oversteer if you’re aggressive on the throttle, but BMW’s stability control nanny cannot be disabled and the intervention is early and aggressive. Toss in the range extender’s 300+ pounds and understeer is a more frequent companion. You can still get the REx a little tail happy if you try however. The i3 will never be a lurid tail happy track car like an M235i, but the fact that any oversteer is possible in an EV is a rare feat since nearly everything else on the market is front heavy and front wheel drive. Put simply the BMW i3 is the best driving and best handling EV this side of the Model S.

Now let’s talk range extender again. After hearing the complaints about the i3’s “limp” mode when you’re left with just 34 ponies, I tried to make it happen to see what the fuss was about. I hopped in the car with the battery at 6% and started off to work. Climbing from 700ft to 2,200ft worked out just fine at 45-50 MPH on a winding mountain road, going down from 2,200 to sea level at 60 MPH was uneventful as well. I hopped on CA-85 and set the cruise control to 65 since the rumor mill told me the top speed would max out at 65ish with the battery dead. 15 miles later my battery was still very much alive so I kicked it up a notch to 75 and switched over to Interstate 280 where rolling hills would tax the battery further. 20 miles later the range extender was humming like a dirt bike in my blind spot but I wasn’t slowing down. I decided drastic measures were needed. I kicked the i3 up another notch to [intentionally left blank] MPH and watched as the battery gauge ran to zero. Finally. Except it wasn’t that exciting. It didn’t feel like I hit the brakes, it simply felt like someone had backed off the throttle. It took me around 1.5 miles to drop from [intentionally left blank] MPH to 55 MPH which was more than enough time for me to put my tail between my legs and move four lanes to the right.

Hitting the “34 HP barrier” as I started to call it proved a little easier at closer-to-legal speeds when hill climbing, and the effects were a little more drastic. On a winding road where driving a car hard involves heavy braking before corners and full throttle exits, the i3 ran out of steam after 4 miles. The i3 then spent the next 8 miles with the go-pedal on the floor at speeds ranging from 37 to 50 MPH.

When running on the range extender, I averaged 60-65 miles before I refilled the tiny tank which came out to somewhere around 38 MPG. The number surprised some, but personally it sounds about right because the energy losses in a serial hybrid can be high (up to 20% if you believe Toyota and Honda). What did surprise me is just how livable the i3 REx was. Despite BMW constantly saying that the REx wasn’t designed to be driven like a hybrid, over 300 miles of never charging I never had a problem driving the car just like I’d drive a Prius, only stopping more often for fuel. Way more often. The i3 REx can drive from San Francisco to Los Angeles stopping every 60 miles for gas, I’m not sure I’d do that, but it is nice to know I could.

Starting at $42,400 in EV form and $46,250 for the REx model, the i3 has the same kind of sticker shock as all EVs. However if you qualify for the maximum incentives the i3 REx comes down to a more reasonable $36,250 which is a little less than a 2015 328i. That slots the i3 between the rabble and the Tesla and more or less the same as the Mercedes B-Class, the only real i3 competition. In this narrow category the i3 is an easy win. It is slightly more fun to drive than the B-Class, a hair faster, considerably more efficient, has the ability to DC fast charge and the range extender will allow gasoline operation if required. The i3 is funky and complicated and BMW’s 320i is probably a better car no matter how you slice it, but none of that changes the fact the i3 is probably one of the most important cars of our time. Not because the i3 is a volume produced carbon fiber car, but because we are likely to see may more “BEVx” category “range extending” vehicles in our future (for more unicorn credits) and this is now the benchmark.

BMW provided the vehicle, insurance and 1.9 gallons of gasoline for this review.

Specifications as tested

0-30: 3.0 Seconds

0-60: 7.0 Seconds

1/4 Mile: 15.5 Seconds @ 86 MPH

Alex L. Dykes
Alex L. Dykes

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3 of 63 comments
  • KixStart KixStart on Mar 23, 2015

    The actual range of the vehicle is much closer to 500 miles if you stuff the cargo area full of gas cans. There's quite a few things to like about this car. It's interesting to see that BMW chose to make some creative decisions about drive-train, layout, doors, construction. It's much more of a "car of the future" attempt than the Volt. However, from a practical perspective, the tiny gas tank means that it's actually more of a Leaf competitor than anything else. I think I'd be more likely to buy a 200-250 mile EV that had fast-charge capability. As for the interesting accelerator pedal characteristics, it reminds me of the BelchFire 8, as shown in National Lampoon from the mid-'70's, with its "Tap-a-Toe" transmission. However, in this case, I would think you could just use the cruise and be perfectly happy.

  • Wmba Wmba on Mar 27, 2015

    Subsequent to reading this review, I read this one: It's a must read. it's detailed. The car seems actively dangerous in snow, because of that strange throttle action. Back off the throttle and the back wheels lock up and spin out the car due to the over eager braking. And adding Blizzaks probably isn't going to help much.

    • Number9ine Number9ine on Jan 09, 2016

      Their i3 was on the 20" wheels which come with summer tires. The "detailed" review left out that important detail.

  • El scotto The days of "Be American, buy America" are long gone. Then there's the mental gymnastics of "is a Subaru made in Lafayette, IN more American than something from gm or Ford made in Mexico?" Lastly, it gets down to people's wallets; something cheap on Amazon or Temu will outsell its costlier American-made item. Price not Patriotism sells most items. One caveat: any US candidate should have all of his/her goods made in the USA.
  • FreedMike Well, here's my roster of car purchases since 1981: Three VWsTwo Mazdas (one being a Mercury Tracer, full disclosure)One AudiOne FordOne BuickOne HondaOne Volvo I think I hear Lee Greenwood in the background... In all seriousness, I'd have bought more American cars had they made more of the kinds of cars I like (smaller, performance-oriented).
  • Kwik_Shift_Pro4X I'll gladly support the least "woke" and the most Japanese auto company out there.
  • Jmo2 I just got an email from the dealership where I bought my car and it looks like everything has $5k on the hood.
  • Lou_BC I suspect that since the global pandemic, dealerships have preferred to stay with the "if you want it, we will order it" business model. They just need some demo models on hand and some shiny bits to catch the impulse buyer. Profits are higher and risks lower this way.