An upside-down car loan is the less onerous euphemism for saying that they owe more on their car than they could ever get if they sold it or traded it in. Is this a bad thing? And if you are one of the four upside-downers what, if anything, can you do about it?

Owing more on your car that it is worth is not necessarily a bad thing if you intend to keep the car until it's paid off, and you have the auto insurance coverage to satisfy the loan if the car gets totaled in an accident. Doing nothing is always an option.

If you are looking to replace the car then you have to do something to close the gap in the unpaid balance of your current loan and the car's resale value, or be prepared to eat the difference and go even deeper upside-down on your next car purchase.

Some new car lenders will add the amount of the unpaid principal on your old loan to the principal amount on your new car loan. In effect you would be paying that much more for your new car, or still paying for the old car you no longer own, which ever way you want to look at it. Do that a couple times and you've paid for somebody else's Hawaii vacation.

If your current car loan contract doesn't have a prepayment penalty, you can refinance your current car loan. Refinancing home mortgages to get a better APR is a national pastime but not nearly as many people have done the same with the second most expensive thing they own. Interest rates change all the time and it may be worthwhile to investigate this route. Even if you refinanced at the same rate for a shorter term, your monthly payment would be higher, but you would get out of the negative equity situation faster too.

Pay your current lender extra every month. This can close the gap in a hurry but only if your lender has agreed ahead of time that all the extra money you send will go to paying down the principal balance on the loan. If you just add something extra to your loan payment without working it out first, the lender will most likely just credit the extra toward a future payment. There is no advantage to you paying extra unless the principal portion of your car loan is being reduced proportionately.

Pay off the car loan with a real estate equity loan or a loan from another source. The main advantage to this approach is that you go instantly from upside-down on the car to 100% ownership. You can now sell the car yourself to raise cash for a substantial down payment, or you can trade it in toward the new car.

Car loan amortizations are set up so that the money from most of your early payments goes almost entirely to the interest portion of the loan. During the first two years of the loan, the resale value of the car plummets while the principal portion of the loan barely budges. The sooner in the loan cycle you address your upside-down loan the better off you will be.