Depends if you would invest the money... s&p, small-cap, and international indexes (or wtf the plural is), money equally divided between, have averaged 12% something per year over the past million years.
If you're just gonna blow the money, might as well pay cash.
DO NOT get gap insurance at the dealer!!!!! Your auto insurer can get you this much cheaper. (Gap insurance covers you for if your car is totalled and you owe more than it is worth)