Dummy guide to how hybrid engine works.
Hybrid car engines uses both internal combustion engine and electric motor for running the car intelligently. The electronic system decides when to run the car on electric motor alone, when to run it on both electric motor and engine, when to run it on gasoline alone and when to use motor as a generator and convert kinetic energy from the wheels into electricity to charge the battery.
When the car is running at low speed electric motor could alone take the charge. When the car put brakes or goes downhill the battery is charged. As the engine starts and during its initial acceleration electric motor is used for the motion and engine comes in when car needs rapid acceleration. When the car is still engine is shut down and the car runs on electric motor thus saving fuel and reducing emission. During full-throttle acceleration or under heavy load, the motor gets a power boost from the battery.