Active Fuel Management (AFM) is a trademarked technology used by General Motors to improve fuel economy on their gasoline engines. The system can shut down half of the engine's cylinders when full power is not needed, such as during highway cruising.
The benefit of AFM is an improvement in fuel economy of up to 5% for V8 engines and up to 12% for V6 engines. GM began using AFM in light-duty trucks and SUVs in the 2007 model year, and expanded its use to passenger cars in 2008. As of 2016, most GM vehicles with gasoline engines are available with AFM.
Critics have argued that AFM can cause engine wear and decreased performance, but GM has defended the technology as being reliable and backed by extensive testing.