The search goes on by auto manufacturers for a car powered by electricity. The latest effort, by Chevrolet, is an evolutionary step: Part gasoline engine, part electric motor. However, it is different than the hybrid combos that have been on the road for several years.
Remember that hybrids have a gasoline engine with power directly to the drive wheel. A small electric motor is mounted behind the gas engine that will run the car at slow speeds, typically on city streets; at high speed, where more power is required, the gas engine automatically starts.
A battery pack stores and releases the electric energy. The electric motor turns into a generator, recharging the battery driven by the gas engine. When the car slows down, the generator side of the electric motor also charges the battery. All of this results in significant fuel savings.