The common definition of a hybrid car is one that uses a traditional petrol engine combined with an electric motor (or set of electric motors) to provide power for the car.
The way that the power from the electric engine is generated and applied differs from car to car.
Normally, in a HEV (Hybrid Electric Vehicle), the petrol engine charges an electric generator which in turn powers an electric motor.
In a PHEV (Plug-in Hybrid Electric Vehicle) the battery is charged by plugging the car into a power socket.
The electric motor often provides power during low-speed acceleration, with the petrol engine taking over at higher speeds, or when the generator needs to be recharged.
The generator can also be recharged through energy created by friction under braking, depending on the car.
In some performance cars the power from the electric motor is added to the power from the petrol engine to further increase the performance of the car.
HEVs are a good alternative to PHEVs and fully Electric Vehicles (EVs) when you don’t have the ability to plug the car in to charge at home.