2005 GMC Envoy Owner's Manual - Page 98

Displacement on Demand (DoD) Your vehicle's engine may be equipped with Displacement on Demand (DoD). This system allows the engine to operate on either four or eight cylinders, depending on your driving demands. The system determines when to switch into and out of the four-cylinder mode by first making sure that certain enabling criteria are met, such as coolant and oil temperatures, and the transmission being in either THIRD (3) or FOURTH (4) gear. When greater power demands are required, such as accelerating from a stop, passing, or merging onto a freeway, the system will maintain eight-cylinder operation. When less power is required, such a cruising at a constant vehicle speed, the system will automatically enable the four-cylinder mode, allowing your vehicle to achieve better fuel economy. Automatic Transmission Operation There are several different positions for your gear shift lever. PARK (P): This position locks the rear wheels. It is the best position to use when you start the engine because your vehicle cannot move easily. 2-24