Well, it's a pure series hybrid, so, apart from the engine itself, it doesn't actually add too much complexity. It's a very small engine (650cc motorcycle engin

Well, it's a pure series hybrid, so, apart from the engine itself, it doesn't actually add too much complexity. It's a very small engine (650cc motorcycle engine) and there's never any direct connection to the drivetrain. The Volt engine is 1.4 liters and there's several clutches to hook it into the drivetrain at various speeds/modes. The BMW Rex is so close to perfect, that I think a lot of people are getting it with the hope that maybe they will be able to swap in a larger tank somehow later down the road. The tank right now isn't even 2 gallons. It's pathetic, and done to get some kind of damn sticker in California, not for any practical reason. Make that a 6-gallon tank with some after-market solution, though, and you've got a car with an 80-mile electric range and then several hundred more miles on gas for road trips.