Car Loan Debt
The best advice for car loan debt or being upside down on your car loan is to keep your car. Making the payments on the car and keeping it, will establish good credit. Cars depreciate quite a bit after you buy them and for three or four years, afterward. After some time, you may be able to sell the car for its blue book value and break even on what you owe on it.
If there are no penalties for doing so, one option would be to pay more on your car than the payment is. If you make larger payments each month, it could reduce the amount of interest you will have to pay or you may be able to sell the car sooner.
It's probably best not to trade the car for another new car that's cheaper, in an attempt to get out of the debt that way. If you can refinance your car, for a shorter term, with a lower loan interest rate this is a consideration.
There is no easy solution for dealing with unwanted car loan debt. Once you have bought it, it is yours. The best remedy is paying it off as soon as you can or just make your regular payments.
In the future it may serve as a good lesson in buying cars. Buying a used car in the future that is three to four years old is still relatively new, but it has depreciated in value to the point it is a good deal. Having a 40% down payment on a car that is predicted to have good resale value in the future is a good rule of thumb for buying a new car and the inevitable new car loan that comes with it. That percentage of a down payment is very high compared to what other experts suggest. But a 40 % down payment puts what you can truly afford in perspective.
If you find a car that has a good resale value and is priced at 20,000$, you will need an 8,000$ down payment. This will probably get you a better interest rate on a loan. Making a loan that is less than four years in duration, will also help. It will also more than likely keep you from ever owing more than the car is actually worth, throughout your payments on the car. If it's a car with a great resale value, after three years you could trade it in on another car, keeping yourself in a new car every three to four years, if done this way.