If you have a C7, most likely you have a battery tender for it - so the battery doesn't go dead when you store it.   How about when you take it someplace and you want to ensure the battery doesn't go dead, and you don't have a tender?   The C7 has Transport Mode just for occasions like this.  Its an easy feature to use to save some battery when you need to.   Here is how it is done -

1. To turn the Transportation Mode on or off, it will be necessary to have all the doors closed.
2. Start the vehicle.
3. Activate the hazard flashers.
4. Press the brake pedal (automatic transmission) or clutch pedal (manual transmission).
5. Press and hold the Start/Stop button or turn the ignition key to the crank position for 10 to 15 seconds. The battery light will flash and the engine will start, but continue to hold the start button/key for approximately 10 to 15 seconds.
6. You will notice the radio will illuminate and the “Transportation Mode” message will disappear allowing you to be able to read the mileage.
7. The same steps are used to turn the Transport Mode feature on or off.

BTW, if you drive the car 50-150 miles with transport mode enabled, , it will disable itself.