See also:

Fuel Additives
To provide cleaner air, all gasolines in the United States are now required to contain additives that help prevent engine and fuel system deposits from forming, allowing the emission control system to ...

Potential Issues
Some OnStar services are disabled after five days. OnStar cannot perform Remote Door Unlock or Stolen Vehicle Assistance after the vehicle has been off continuously for five days. After five days, OnS ...

New for 2011
The Sierra Hybrid gets GM's OnStar 9.0 telematics system that GM says provides better voice recognition. GM also said they have worked to cut down on the amount of wind noise occupants hear. ...