Take your car in for an annual tune-up. Think of this as the car's physical, and schedule tune-ups more frequently if you put your car under a lot of stress (do you tow things? live in Death Valley?).

Where to have it done:

If you don't have a maintenance warranty, you'll need to weigh the pluses of a dealership (familiarity with your make of car, availability of parts) against an independent mechanic (who may be cheaper or more conveniently located). Ask friends for recommendations, or check the Mechan-X-Files at the website of the Car Talk radio show (www.cartalk.com). Whether you choose an independent or dealership mechanic, look for a certificate of Automotive Service Excellence (it should be on the wall, among the calendar beauties; it means that the mechanic has at least two years' experience, receives ongoing training, and is recertified every five years). Tune-up shops may charge lower rates than either a mechanic or a dealership, but using a tune-up shop means you have fewer chances to make friends with a mechanic who can help you when something goes wrong.

What a tune-up should include:

"Routine replacement of spark plugs, filters, and other air, fuel, and ignition related parts, plus a precise series of tests and adjustments performed to regain maximum engine performance and fuel economy,"— from Car Smarts, by Mary Jackson (John Muir Publications).