A hybrid vehicle is a vehicle that uses a combination of gas and electric power. Conventional automobiles have a single gasoline engine that provides power for the wheels and the electrical system. In a hybrid car, the engine doesn't usually drive the car. Instead, it runs as a generator, charging up batteries that power one or more electric motors. Hybrid cars are much more efficient than conventional motors for several reasons.
The Gas Engine
Traditional cars have fairly large, powerful gasoline engines. When the car is accelerating, the engine has to create a lot of power to get the car up to speed. Once the car is at cruising speed, it requires less power to run, but the same big, inefficient engine keeps running anyway. Hybrids use a much smaller gas engine, which turns a small generator called an alternator to generate power for the batteries. The gas engine runs at a constant rate until the batteries are charged to a certain level, then shuts off. When the battery needs more power, the gas engine turns on again. Because it does not produce big bursts of energy like a traditional automotive engine, a hybrid gas engine can be compact and efficient.
The Electric Motors
Hybrid cars often have two small electric motors, one on each of the front or back wheels. When the car needs to accelerate, a computer increases the energy flowing to the electric motors to generate the necessary torque. When the car is cruising or coasting, the computer can slow down the motors or even disconnect them completely, saving more energy.
