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 owners manual will tell you. You can also ask your mechanic what grade of fuel to use. Using regular gasoline over high-octane gasoline could save you hundreds of dollars a year.

Make sure your gas cap is tight. Gas will evaporate from the gas tank if it has an escape. Loose, missing or leaking fuel caps can cause evaporation, so keep your cap tight.