GMC Sierra Owners Manual
Active Fuel Management®
Vehicles with V8 engines may have Active Fuel Management™. This system allows the engine to operate on either all or half of its cylinders, depending on the driving conditions.
When less power is required, such as cruising at a constant vehicle speed, the system will operate in the half cylinder mode, allowing the vehicle to achieve better fuel economy. When greater power demands are required, such as accelerating from a stop, passing, or merging onto a freeway, the system will maintain full-cylinder operation.
If the vehicle has an Active Fuel Management™ indicator, see Driver Information Center (DIC) on page 5‑33 for more information on using this display.