GAP covers the deficiency balance on your loan in the event of a total loss of your vehicle.
In the event of theft or total loss of your vehicle, most insurance companies only pay the Cash Value of the vehicle at the time of the loss. Your remaining loan balance could be much greater than the Cash Value of your vehicle creating a deficiency of several thousand dollars that you're liable for! What is the "GAP" on your vehicle? You may be surprised at the answer!