Stirling engine car: Installed in the car’s trunk compartment is a Stirling engine invented at DEKA, Kamen’s technology company in the Manchester Millyard. It powers the features that would normally drain huge power from the battery, notably the defroster and heater.

That leaves the battery primarily for propulsion. “You’re running a pure electric, which is enormously cheaper to operate and enormously more environmentally friendly,” Kamen explained. [I’ve always enjoyed the small Stirling engine models you buy for your desk… and always wondered why something seemingly so useful, has always been labeled as not useful. Maybe not…]
Source: MAKE Magazine