As soon as you drive a new car off the lot, it loses a good chunk of its value. That’s bad all on its own. Things go from bad to worse, though, if a crash totals it shortly after you bring it home. In that case, your lender will want the full price of the car, but your insurance company only will pay you its used “Blue Book” value. Gap insurance keeps you from having to worry about this. It pays the difference between what you owe and what you’ll be paid if an accident totals your new car.