See also:

Battery Load Management
The vehicle has Electric Power Management (EPM) that estimates the battery's temperature and state of charge. It then adjusts the voltage for best performance and extended life of the battery. ...

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. ...

Hydraulic Power Steering (3.0L V6 Engine)
If power steering assist is lost due to a system malfunction, the vehicle can be steered, but may require increased effort. ...