An engine is a generator that produces mechanical force and motion from another form of energy (eg a fuel source, compressed gas (eg air) or electricity). It is also referred to as a prime mover. An automobile makes use of several motors to start the car and drive the car's various pumps (fuel, power steering, etc) – but the power plant that propels the car is called an engine. The term 'motor' was originally used to distinguish the new internal combustion engine -powered vehicles from earlier vehicles powered by a steam engine (as in steam roller and motor roller).
