* Keep the gas you buy in your car. When gas prices are low, stealing gas would likely be more trouble than it's worth, but when prices are high, it's not uncommon for thieves to siphon gas from vehicles, especially those with larger tanks. Adding a locking gas cap can be done for much less than the cost of a tank of gas. In addition to preventing theft, locking fuel tank caps can also prevent anyone from tampering with your gas tank.
* Keep your tank full. While you're looking to reduce the amount of gasoline you are using, constantly running your car with the tank close to empty can wear down your fuel pump. "The gasoline in the tank keeps the fuel pump cool. Take away the gas and the fuel pump runs hot and has a shorter life," says Tom Taylor, engineer and vice president of RockAuto.com. If you have an older car that has accumulated dirt and rust at the bottom of the tank, keeping a full tank can help your fuel burn cleaner.
* Keep your car in shape. Keeping your engine properly tuned improves fuel efficiency by an average of 4 percent and repairing a major issue like a faulty oxygen sensor could improve efficiency by up to 40 percent, according the U.S. Department of Energy. The RockAuto.com parts catalog has oxygen sensors from $10 to more than $100 depending on the car," says Taylor. Especially if you're a do-it-yourselfer, you could quickly recoup the cost of an oxygen sensor or other repair after as little as one tank of gas through improved fuel economy.
* Keep your tires inflated properly. Keeping your tires at the optimal level not only keeps you safer, but can improve your gas mileage by up to 3.3 percent, according to the Department of Energy. Your owner's manual should tell you the proper psi (pounds per square inch) levels for your vehicle.
* Drive for optimal gas mileage. How you drive can affect how much gas you use. Most cars run at peak efficiency at around 60 mph, with fuel economy decreasing sharply when traveling faster. Aggressive driving with rapid acceleration and slowing will also have a negative effect on your fuel economy.
* Reduce weight and drag. Getting rid of items such as roof equipment when they aren't being used can help your car become more aerodynamic and run more efficiently. Keeping unnecessary items in your car, especially if they are heavy, can also make your car work harder and use more fuel than it needs to.
By adding up the small savings gained by each of these tips, you can really notice a difference on how much you are paying at the pump, especially over a long period of time.