See also:

Sunroof
If the vehicle has a power sunroof it will only operate when the ignition is in ON/RUN or ACC/ACCESSORY, or when Retained Accessory Power (RAP) is active. See Ignition Positions (Key Access) ...

Trailer Towing (CTS-V and Coupe)
The vehicle is neither designed nor intended to tow a trailer. ...

Entering the Feature Settings Menu
1. Turn the ignition on. To avoid excessive drain on the battery, it is recommended that the headlamps are turned off. 2. Press the customization button to enter the feature settings menu. ...