Instead of recharging through a plug, the batteries get their juice from a small, light gasoline or diesel engine. When you hit the brakes, kinetic energy is converted into electricity, then stored in the battery. At a stop light, the engine shuts down entirely. Because the battery is not the car's sole source of support, so to speak, it can be much smaller than the weighty, costly monsters used for battery-operated cars. But even hybrids could seem passe by 2004, when major auto makers promise to start selling cars powered by fuel cells.
Fuel cells make electricity without burning anything.
They don't even have moving parts .