2008 GMC Envoy Owner's Manual - Page 100

Automatic Transmission Operation There are several different positions for your gear shift lever. {CAUTION: It is dangerous to get out of your vehicle if the shift lever is not fully in PARK (P) with the parking brake firmly set. Your vehicle can roll. Do not leave your vehicle when the engine is running unless you have to. If you have left the engine running, the vehicle can move suddenly. You or others could be injured. To be sure your vehicle will not move, even when you are on fairly level ground, always set your parking brake and move the shift lever to PARK (P). See Shifting Into PARK (P) on page 2-34. If you are pulling a trailer, see Towing a Trailer on page 4-45. 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. 2-26