Hybrid cars are the intermediate step between green life and what we have right now. Although long overdue, it finally became available to the public.
The concept is easy: you take a regular engine and modify it so that the engine can use additional electric power to produce kinetic energy. In one word, using a lower fuel consumption to generate both kinetic energy, to move the car, and electric energy to recharge the batteries. In the same time the energy generated or stored for that matter, is used to power a small electric motor in order to generate additional kinetic energy to move the car.
Hope it helped.