CarMax (NYSE:KMX), a firm that sells used cars online, recently conducted a poll on its website, and found that 78% of car buyers experienced remorse within a few days of buying a new car.

If you're in the market for some new wheels yourself, get a little information under your belt before you buy, so you don't end up as part of that statistic. Money magazine recently listed a bunch of car-buying commandments. Here are a few, with some additional Fool commentary:

  • Know the numbers. Don't begin to negotiate a price without a good sense of the fair value of the vehicle you want. You can look up detailed prices at sites such as and Kelley Blue Book's

  • Separate the car from the deal. Focus on the car you want and don't let your mind start evaluating other deals available on other vehicles. Aim to find the best deal only after you've found the best vehicle.

  • Don't get lured by rebates. Money notes that, "The very best cars, such as the Toyota (NYSE:TM) Corolla, are top values even at the full retail price. Other cars require rebates simply because most people wouldn't buy them otherwise. That discount can lower your monthly payment. But expect every penny of that rebate, and often more, to disappear from your car's long-term resale value."

  • Shop the money. Look into your credit rating and available interest rates and loans. If possible, get pre-approved for a loan -- but don't mention that until your price is agreed on. (You can learn more about credit scores at our Credit Center.)

  • Play the dealers off each other. We've long recommended this at the Fool, beginning with our "fax-a-thon" approach. You can now achieve similar results online, but the point remains the same: By challenging dealers to offer you a better price than other dealers have offered you, you stand a good chance of getting a good deal.

You'll find more money-saving tips and guidance at our Buying a Car area and our Buying and Maintaining a Car discussion board.

Longtime Fool contributor Selena Maranjian doesn't own shares of any of the companies mentioned in this article. But she does own a car.