Many car dealers will allow you to trade in your older vehicle for money towards a new one.

A method of selling used cars that is gaining popularity is the trade-in method. Quite often, your car dealership will accept your used car and give you money in exchange that you can use towards a new car from them. While this limits your options (as the dealer will only allow you to buy a car from their dealership) for new cars, it also ensures that you will get a reasonable price, as the dealers wish to give you incentive to buy from them again. However, while this process may seem simple at first, there are a few things you should keep in mind before agreeing to any deal.
Do Your Homework!

According to www.automotive.com, you want to know just how much your car is actually worth. If you were selling to a private buyer, you would never accept less than the true value of the car, so you should do the same with regards to a dealership (for more information on car values, see 'Determining an Asking Price').
Protect Yourself

The web site above warns that dealers will usually try to give you less than the car's true worth in trade-in value, simply because the nature of the dealership is to try and maximize profit. In order to avoid suspicion, dealerships will often offer trade-in 'allowances,' which are simply offers for your car that are contingent upon you buying another one from them. This may often seem like a great deal, but generally the dealer will include separate charges with your new purchase in order to compensate for lost profits. It is best to try and avoid allowances entirely, but if you are still interested, it is recommended that you simply be aware of the risks involved with them.
Should You Make Repairs?

Some questions that may come up when you are considering a trade-in are whether or not you should repair the car first, or how much tire damage matters in the car's appraisal. Well, the answer to the former question is simply that it depends. Small repairs may add value to your car, but you should spend a great deal on anything major, since the dealership will likely take care of that itself. As for tires, it seems that mismatched tires can detract a great deal from the value of your car, simply because of alignment and aesthetic issues.

One of the most important things to remember when researching dealer trade-ins is that you should always have your fluids and belts checked and/or replaced if needed. These are cheap fixes that could go a long way towards ensuring that you get the most money for your trade.