With its space-age body, super-efficient powertrain, and laser focus on its urban mission, the i3 pushes the boundaries in automotive design. This tall, narrow, electric city car not only looks like a futuristic personal transportation pod that just drove off the set of the latest "Tron" movie, it's the first widely available car to use lightweight carbon fiber for its basic body structure. That single mission focus contributes to makeing the i3 the most energy-efficient car we've ever tested.
The i3 has a typical 75-mile range before the charge runs out. The 94Ah version comes with a larger battery (33 kWh) and extents that range to a claimed 114 miles. Unfortunately, U.S. customers won't be able to retrofit the new battery, at least for now. We bought our i3 with the optional two-cylinder gasoline range extender (REx). Think of it as an onboard home generator that continues to provide electricity when battery power depletes. It's designed to reduce range anxiety, but as we found in our testing, it's not really supposed to be used as the primary power source. Think of it as a set of training wheels for electric-car newbies. Most i3 buyers are opting for this $4,000 option.
BMW makes it clear that the i3's range extender isn't meant for continual use by giving it a miniscule 1.9-gallon gas tank. We averaged a mere 50 additinal miles in that mode. The improved 94Ah version gets an enlarged tank of 2.4 gallons that's likely to add about 20 more miles. Cross-country journeys are possible as long as you don't mind filling up once an hour. Moreover, the i3's gas consumption is no better than low 30s mpg, undermining the car's effciency in electric mode.