See also:

OnStar Overview
If equipped, this vehicle has a comprehensive, in-vehicle system that can connect to a live Advisor for Emergency, Security, Navigation, Connection, and Diagnostic Services. The OnStar system s ...

Running the Vehicle While Parked
It is better not to park with the engine running. But if you ever have to, here are some things to know. WARNING Idling a vehicle in an enclosed area with poor ventilation is dangerous. Engine e ...

Powertrain details
The GMC Sierra All Terrain HD concept is propelled by the new, production 6.6L Duramax turbo-diesel V-8 and Allison 1000 six-speed automatic transmission powertrain combination offered in the 2011 ...