Inflate those tires. Soft tires slow you down and can cut gas mileage by 10 percent or more, according to the tire-sales and research website www.tirerack.com. Follow the inflation instructions in your owner's manual or on the decal at the inside edge of the driver's door. Ignore the numbers on the tire sidewall, as they are more general and not specific to your make of car. Aim to check your tire pressure once a week — at least once a month is crucial. Keeping tires properly inflated will also help you avoid rollover and other tire-related accidents.

Maintain the engine. A reduced air supply or a sluggish ignition can cut into mileage. Change the air filter twice a year and the spark plugs every 50,000 miles. When you change the oil every 6,000 to 7,500 miles, have the mechanic check your cooling system, too. Even cars with computer-controlled engines, which need fewer tune-ups, require these chores.

Take a load off. Extra weight in the car can hurt mileage. Reduce the clutter in your trunk by removing tools, golf clubs, and other weighty and hardly used items.