Why The BMW i3 BEVx Won’t Get ‘180 Miles Per Charge’ As BMW Suggests

If an electric car comes with an on-board range-extending gasoline engine, should its range per charge be given excluding or including said range-extending engine?

BMW's official i3 microsite quotes the i3 BEVx as having up to 180 miles per charge range.

BMW’s official i3 microsite quotes the i3 BEVx as having up to 180 miles per charge range.

Traditionally, automakers have erred towards the side of caution, quoting range per charge as an ‘all-electric’ figure, but BMW USA has broken from the pack, advertising its 2014 BMW i3 BEVx range-extended electric car as having a ‘range per charge’ figure which includes both gasoline and electricity.

Bigger range?

On the front page of its BMW i3 BEV model microsite, BMW proudly proclaims the all-electric variant of the i3 to have a range of somewhere between 80 and 100 miles per charge.  Although official U.S. economy figures have yet to be released for the i3 or the i3 BEVx, what we know of European range estimates — and the fact that they are notoriously optimistic — we’d say BMW’s quoted range is reasonably accurate.

Yet on the BMW i3 BEVx model microsite, BMW quotes the range per-charge figure for the i3 BEVx as being between 160 and 180 miles.

A technicality of nomenclature

On paper this would appear to indicate the BMW i3 BEVx has a larger battery pack than its all-electric sibling. In reality however, this isn’t true: the BMW i3 BEVx and BMW i3 BEV are identically specced in terms of battery pack, electric motor and charging circuit.

So what’s going on? To explain, we think it’s worth looking at the way in which the car works.

The BMW i3 BEVx is sold as an all-electric car with a range-extending gasoline engine on board. Its purpose is to extend the useable range of the i3’s lithium-ion battery pack in emergency situations when there isn’t quite enough charge to reach the next charging point.

Unlike the Chevrolet Volt and the Toyota Prius Plug-in Hybrid, which will both run quite happily in gasoline-only mode for extended periods of time, the BMW i3 BEVx’s engine isn’t designed to operate for long periods of time. It’s something you’ll probably never really use — unless there’s an emergency, you need to go a little bit further than your car can comfortably cope with, or you have a charging station malfunction.

The i3 BEV is quoted with the more acceptable 80 miles range.

The i3 BEV is quoted with the more acceptable 80 miles range.

Further, unlike the Volt or Prius, whose engines stay off until the battery pack is completely depleted, the BMW i3 BEVx in certain markets comes with the ability to switch on the gasoline engine before the battery pack is empty. This has the effect of slowing down the rate at which the battery pack is depleted, since electricity from the battery pack is being supplemented by the on-board generator.

With that in mind, we’re guessing BMW executives think of the gasoline range-extender as literally enabling further all-electric range.

This leads to some very clever math, where range per charge could be seen as being equivalent to electric+gasoline. 

Not ‘all electric’

Of course, the challenge here is the fact that while BMW is technically correct that ‘range per charge’ is as much as 180 miles, ‘electric only range,’ or range where the battery pack alone has provided motive power, remains at somewhere between 80 and 100 miles, depending on driving style.

Further still, because of the weight of the gasoline tank and range-extending engine, expect the BMW i3 BEVx to travel slightly less far per charge in all-electric mode than its all-electric sibling.

Won't car buyers get confused? What about dealers?

Won’t car buyers get confused? What about dealers?

Had BMW quoted a ‘total range’ figure alongside an ‘all-electric’ figure, we’d be far happier — and we suspect many buyers would be too.

Caveat emptor

With so much confusion already in the electric car marketplace surrounding real-world range and charging requirements, we think it’s unfortunate that BMW has chosen to break from the normal nomenclature used when advertising plug-in hybrids and range-extended electric cars. Given the infancy of the market and the naivety of many of its would-be customers, we think quoting combined range figures as ‘per charge’ only serves to alienate rather than educate.

Moreover, with many salespeople using official automaker websites to provide ‘backup data’ for their own sales, we can see situations arising where customers — who do not fully understand the subtle difference between range and all-electric range — buying a car believing it to travel almost double the distance it is capable of in electric-only mode.

But what do you think? Is BMW being fair? Is this one nuance too far?

Leave your thoughts in the Comments below.


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  • Michael Thwaite

    If the i3 Range Extender were in fact a bigger battery instead of a motorbike engine in the boot, I’d be shouting out to the world that the EV for the masses is here and they’re welcome to view the one on my driveway!

    • CDspeed

      I think calling a car “range extended” should only apply to cars with optional battery sizes, so the 85 kWh Tesla Model S is the range extended version of the base 60 kWh Model S. And I agree, a battery option would have been better, it seems odd that the more expensive version of this small electric car requires oil changes.

    • vdiv

      It is sad that BMW designed the REX to get an HOV sticker, which now it seems it won’t. With all of that fancy new CFRP monocoque lightweight body, skinny seats and tires it is really unfortunate that the I3 did not push the range envelope beyond 100 miles.nnStill, kudos to BMW for finally selling an EV!

  • CDspeed

    I don’t think BMW meant in anyway to suggest that the car has more electric only range with the REX equipped cars. I understood BMW’s website, REX equipped i3s have a total range of up to,160 to 180 miles. Because Chevrolet separates the electric range from it’s range extended mode, I’ve met people who think that the Volt only goes 38 miles. They hear the electric range and thats it, so by their thinking the Leaf actually has more range, until you tell them about the generator. I think BMW’s combined range estimate is actually less confusing, if I buy the pure electric version it goes 80 to 100 miles, if I buy the hybrid version it goes 160 to 180 but will require gas and more maintenance.

    • vdiv

      I think the confusion comes from the “per charge” statement. If the range was identified as a “total range”, or just “range” it would be better. Also since the i3 REX is a dual “fuel” vehicle the range from each “fuel” deserves its own mention.

      • CDspeed

        I agree “total range” would make it clearer and describe it better.

  • “Range” per Charge requires clarification if a drivetrain has more than one power mode. Like-wise; Range-Extended needs mode clarification (Fuel-extended, or DCFC-extended range).nnSuggests:nAll-electric Range: battery only modenCombined Range: total range from both hybrid and battery modesnHybrid-electric Range: using fuel only (typically to reach destination, before switching to the all-electric mode)nService Range: miles between extender engine servicing (oil change, etc)nneg: “I’d be less tempted to stretch my all-electric range if my service-range anxiety had increased.”

  • Neil Stratford

    There is no confusion in the car itself (at least in the UK version.) The EV and petrol ranges are shown separately both on the dashboard display and in the iPhone app.nn’Hold charge’ mode also does exactly what it says – an arrow appears on the EV range gauge showing where it will hold and the petrol gauge then lights up and starts to deplete instead.