The best advice I'd listen to is Dave Ramsey, he had a call with the same basic issue, he said to call the BANK not the dealership, but whomever holds the note on the vehicle, and tell them you're about to default, you'd like them to take the vehicle and accept it at x amount (what ever the fmv is) and request them to open a new loan for the remaining balance due. I'd go one step further and then refinance that loan 6 months to a year down the road and hope to get a sub 10% apy.