Don't top off.
Don't bother topping off when filling your car's gas tank. Any additional gas is just going to slop around or seep out. Why waste your money paying for gas your car won't use? Stop pumping at the first indication that your tank is full when the automatic nozzle clicks off.
Tighten up that gas cap.
Gas will evaporate from your car's gas tank if it has an escape. Loose, missing or damaged gas caps cause 147 million gallons of gas to evaporate each year, according to the Car Care Council. So be sure to tighten up that gas cap each time you fuel up your car.
Go for the shade.
The hot summer sun that makes the inside of your car feel like a sauna also zaps fuel from your gas tank.
"If you let your car bake in the sun there's going to be a greater amount of evaporative emissions that take place than if you park in the shade," says Jim Kliesch, research associate at the American Council for an Energy-Efficient Economy and vehicle analyst for GreenerCars.com.
So park your car in the shade of a building or tree whenever possible. And buy a good windshield shade. A windshield shade blocks sunlight and helps to keep heat out of the inside of your car.
Use your garage for your car.
Got a garage? Clear it out and make room for your car. Parking in your garage will help your car stay warm in winter and cool in summer, and you won't have to depend as much on your gas-guzzling air-conditioning or defroster when you drive.
Pump up your tires.
Don't get caught driving on under inflated tires. Under inflated tires wear down more quickly and they also lower your car's gas mileage.
"Tires that have low pressure offer more resistance so the engine is going to work harder to keep the car at 60," says Brian Moody, road test editor at Edmunds.com.
Your car's gas mileage may plummet by as much as 15 percent. Driving on under inflated tires may also reduce the life of your tires by 15 percent or more.
Check your tire pressure once a month.
Buy a digital gauge and keep it in your glove box. Compare the pressure in your tires with the recommended pressure listed in your owner's manual and on the placard in your car door. Then inflate your tires as needed. Be sure to check tire pressure when your tires are cold. A good time is early in the morning after your car's been idle overnight.
Keep your engine in tune.
Fixing a car that is out of tune or has failed an emissions test can boost gas mileage by about 4 percent. So be sure to give your car regular tune-ups. You'll also want to watch out for worn spark plugs. A misfiring spark plug can reduce a car's fuel efficiency by as much as 30 percent.
Replace air filters.
Keep a close eye on your engine's air filter. When the engine air filter clogs with dirt, dust and bugs, it causes your engine to work harder and your car becomes less fuel-efficient. Replacing a clogged air filter could improve your gas mileage by as much as 10 percent and save you 15 cents a gallon. It's a good idea to have your engine air filter checked at each oil change. The Car Care Council recommends changing your car's air and oil filters every three months or 3,000 miles or as specified in your owner's manual.
Use the right oil.
You can improve your car's gas mileage by 1 percent to 2 percent by using the manufacturer's recommended grade of motor oil. Opt for motor oil with the words "energy conserving" on the API performance label. This oil contains friction-reducing additives.
Don't skimp on maintenance.
Be serious about auto care. Your car's performance depends on it.
"Always follow the manufacturer-recommended maintenance," Moody says. "The car's designed to run a certain way. If you neglect it, it won't be as efficient."
Obey the car-care guidelines outlined in your owner's manual