Range anxiety; it ‘s what holds many back from buying an electric vehicle and why BMW has done some serious R&D into a range extender for the i3. Truth be told, this is the car we are interested in adding to the stable and not the pure electric model and its not because of range anxiety- it ‘s the being prepared mentality we religiously follow. You just never know when you may end up in a ditch avoiding oncoming traffic in a snow storm and might need that juice to stay warm a bit longer waiting for a flatbed or just have an unexpected detour. That is one of the plusses of a range extender.

The ReX, as it is often called, in the i3 is rumored to be a small 650cc two cylinder engine derived from BMW ‘s Motorad division that ‘s mounted under the rear floor to power a generator. The fuel supply will be a small gas tank (3 gallons) up front to provide an additional 80 miles of driving. Sounds great right? According to greencarreports, there may be a hitch. Herbert Diess, global R&D boss for BMW, explained the company ‘s point of view, reinforcing the viewpoint cited at the launch: The range extender is not intended for daily use. It ‘s for situations when the driver needs to extend the range of the vehicle to reach the next charging station. Therefore, the i3 probably won ‘t be the choice for customers with a need for an extended range.

This view of BMW basically shows their hand in terms of what the i3 will be in ReX mode without officially letting the cat out of the bag; it will be a “limp mode “. This is in stark contrast to the Chevy Volt that provides nearly identical performance in electric and ReX modes as needed.

Diess says that BMW doesn ‘t think the range extender will be needed by a “substantial share ” of i3 buyers:

It is more of an issue for those who have not yet had a chance to use an electric car. After a few days, they usually discover that a base range of [100 miles] is sufficient to limit recharging to about two times a week. In most cases where people first think they need a range extender, it actually never is used.

BMW is not expecting to sell many ReX models after the initial launch because people will begin to realize that they really do not require a vehicle with more than a 100 mile range all that often and when they do, BMW has them covered with loaner cars and a system already being established for car sharing. They may have a point there but that still doesn ‘t help the paranoid and skeptics so BMW may have a hard time pushing that stateside.

We shall see as this all unfolds- regardless of the outcome we are still believers in BMW ‘s commitment to BMWi and even if it falls on its face all that R&D into lightweight building techniques can be transferred over to combustion models. We ‘re waiting on official specs and seat time before we cast our vote on this but sound off in the comments with your take.

UPDATE: BMW has provided us with some additional information and it paints a better picture of the ReX. They have told us that the ReX will of course increase range and while the performance may not be identical to that of a fully charged battery it will not be limping along the interstate or autobahn at 30 mph when the range extender kicks in. You may not have the same power as with a fully-charged battery, but you would be able to drive normally.