A great exercise to go through is trying to figure out how much a car will cost you over its life. It can help you make smart decisions about which vehicles to buy, sell, and keep.

Below are the main factors to consider. For each one, estimate how much you'll spend on it each year, add up all the values, and then multiply the sum by the number of years that you expect to own the car. (To make it more accurate, tweak the numbers to reflect the age of your car each year. Insurance costs are likely to drop somewhat as the car ages, for example, while repair expenses will probably increase.)

  • Purchase price
  • Maintenance
  • Repairs
  • Gas (or other fuel)
  • Insurance
  • Taxes
  • Registration and plate fees
  • Accessories, such as fuzzy dice

These considerations are particularly important if you're thinking of buying a pricey car that you can just afford. You may be able to swing the purchase, but will you be able to afford other, steeper costs that might come along with the car, such as higher insurance premiums and premium gasoline?

Know that some trim models of the same car get placed into higher-premium "sports car" categories by insurance companies, and the cost difference to insure them can really pack a punch to your wallet. Call your insurance company and get an estimate on insurance premiums before you finalize a car purchase, so you won't face any surprises. If a car does seem to cost a lot more to insure than you expected, ask the insurance company why. They may be able to help you identify other models with more reasonable premiums.

For much more scoop on the ins and outs of the car-buying process, check out the Fool's "Buying a Car" area and ask any questions on our "Buying and Maintaining a Car" discussion board.