It's expensive buying a car and it only gets more so as time goes on. Over time, the price of new cars has increased faster than the rate of inflation. This isn't entirely due to greed on the part of automakers; cars are also more complicated and useful than they used to be. Sure, they were cheaper in the 1960's, but they didn't include air conditioning, air bags and video systems. Convenience and safety comes at a price.

With the increase in price comes an increase in the length of time people are taking to pay off their cars. Few people pay cash; most people take out loans and pay over time. The average car loan, which used to be repaid over a period of three years, now averages about six years in duration. That's a long time to pay for a car, especially if you have no plans to own it for that long.

Taking six years to pay for a car has its advantages, as the payments are lower than they would be over a shorter loan term. Such a long loan does have a significant disadvantage, though - you can find yourself in a negative equity, or "upside down", situation. This can be a serious problem - if you should total the car in an accident, your insurance company will only pay you the value of the car, and not the amount you still owe.

A buyer is described as being upside down when he or she owes more on a car loan than the car is worth. It's easy to find yourself in an upside situation, and it can occur under any of the following circumstances:

Insufficient down payment - Cars depreciate as much as 25% the minute you drive them off of the lot. If you haven't provided enough of a down payment to cover that depreciation, you may find yourself upside down immediately.

Trading in too often - Buyers like to trade cars in and roll their outstanding balance into a new loan. These unpaid debts can contribute to negative equity.

Too long a loan - Five and six year loans often lead to negative equity. You can often avoid it by keeping the length of loans to three years or less.

In order to avoid a potential problem in the event of an accident, you should contact your insurance provider to make sure that you have "gap insurance." Gap insurance will make sure that you are protected should you have an accident while in an upside down situation. Without gap insurance, you may find yourself still making car payments even though you no longer have a car. That is the last thing any car owner wants.