Cylinder deactivation
An engine feature that turns off some cylinders when they are not needed, so the engine runs on fewer cylinders and saves fuel.
Cylinder deactivation is an engine feature that turns off some of the engine's cylinders when they are not needed. Fueleconomy.gov states that it saves fuel by "turning off" some cylinders when they are not needed. An eight-cylinder engine, for example, can run on four cylinders and bring all eight back when you ask for more power.
The engine's control system decides when to switch cylinders off and on. The feature may appear under different names, and it is a detail of a combustion engine rather than a separate category of car.
It applies only to combustion engines. Battery electric cars have no cylinders. Fueleconomy.gov lists it alongside turbocharging and start-stop systems as fuel-saving technologies for combustion engines.