Hybrid Cars
Building a hybrid car requires building a car with two drivelines. Now, I recognize that there is a symbiosis between the two drivelines (i.e. regenerative braking), but the net benefit is small, the greater saving comes from not running the gasoline engine when relatively little power is required (low speed cruising, etc.)
The car requires a generator to recharge the batteries, and both a mechanical and electric drive system. My point, in a nutshell, the car would be relatively more efficient if it were a single system. Yes, the choice would make it a compromise - an electric isn't good for long trips (battery life), but is far more efficient for short trips (and it doesn't lose out by hauling a gasoline engine and all its ancillaries around when driving at low speed in and around the city or suburbs).
Check out Zenn Motor Company or Global Electric Motors or at the other end of the spectrum, Tesla Motors. As you will see, some look a bit more car-like than others.