An idea that might work - short sell
It's done with homes that are in danger of being foreclosed on and, to a lesser degree, done with car loans in danger of repossession. It applies to loans that are upside down — you owe more than the car is worth. It's call a short sell. It works best if your car loan is with a local bank or credit union, not so well with a carmaker's finance company such as GMAC or Ford Motor Credit. Here's how it works.

Explain to your bank why you will no longer be able to afford your car and that a repossession is unavoidable. Ask them to allow you to sell the car for a fair market price (check with www.kbb.com and www.nadaguides.com) and agree on a price. Even though the money doesn't fully cover your outstanding loan, the bank agrees to write off the balance and close the loan. In most cases, your credit is not affected. However, you may have to pay income tax on the write off amount since it is kind of gift from the bank. You would pay at the time you normally file your tax return.

Don't expect this tactic to work in all cases. The reason it can work is that, if you sell the car yourself instead of turning it in to the bank, the bank gets more money than if the car is repossessed and sold at a wholesale dealer auction.