Use regular gasoline
Unless your vehicle requires premium gasoline, filling up your car with high-octane gas is a waste of money. The premium gas doesn’t boost your gas mileage or performance. If you're not sure what grade works best for your vehicle, your owner's manual will tell you. You can also ask your mechanic what grade to use. Using regular gasoline over high-octane gasoline could save you hundreds of dollars a year.
Don't top off
Don't top off when filling your car's gas tank. Any additional gas is just going to slop around or seep out. Stop pumping at the first indication that your tank is full when the automatic nozzle clicks off.
Tighten up the gas cap
Gas will evaporate from the 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. 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. 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 located 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. Ensure your mechanic checks for them
Replace air filters
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 vehicle gas mileage by 1 to 2 percent by using the manufacturer's recommended grade of motor oil. Use motor oil with the words "energy conserving" on the API (American Petroleum Institute) performance label. This oil contains additives to lower the friction.
Don't skimp on maintenance
Your car's performance depends on it being properly maintained. The owner's manual of your vehicle will tell you what maintenance is needed and when. If you have any questions, your auto repair shop will be able to show you the recommended maintenance for your car. Follow the car care guidelines outlined in your owner's manual. Not only will they improve efficiency, they will also save you money on costly repairs in the long run.