Under the Hood

GM's two-mode hybrid system enables "full" hybrid operation with the capability to cruise on electric power up to 30 mph. The gas engine kicks in if more acceleration is needed, as well as at higher speeds; for maximum grunt, the electric motors and gas engine work together.

At the heart of the Sierra Hybrid is a 6.0-liter V-8 that teams with GM's Electrically Variable Transmission, which integrates two 60-kilowatt electric motors. The motors draw power from a 300-volt battery pack, which recharges itself off the friction generated when you hit the brakes. The engine makes 332 horsepower and enables a towing capacity of 6,100 pounds with rear-wheel drive and 5,900 pounds with four-wheel drive. That's not as much as the regular Sierra's 10,500-pound maximum towing capacity, but it's not too shabby for a hybrid.

    See also:

    How OnStar Service Works
    Automatic Crash Response, Emergency Services, Crisis Assist, Stolen Vehicle Assistance, Vehicle Diagnostics, Remote Door Unlock, Roadside Assistance, Turn-by-Turn Navigation, and Hands-Free Calling ar ...

    Dome Lamps
    There are front and rear dome lamps. The dome lamp controls are located in the overhead console. To change the settings, press the following: (Dome Lamp Override): Turns the lamps off, even whe ...

    Battery Voltage and Charging Messages
    BATTERY SAVER ACTIVE This message displays when the system detects that the battery voltage is dropping below expected levels. The battery saver system starts reducing certain features of the vehicle ...