Keep your car clean. Mud on the undercarriage can weigh a significant amount and slow you down.

Consolidate your daily trips and errands. This will also save you the cost of restarting your engine, which uses a lot of gas.

Avoid air conditioning when possible. However, when driving at higher speeds, having your windows open also creates drag.

Don’t throttle the gas or brake! Sudden starts or stops use more gas than gradual changes of speed.

Don’t idle for too long. Turn off the engine if you anticipate a lengthy wait.

Limit car warm-ups in cold weather.

Clean out the trunk. More weight in your trunk equals more drag

Avoid high speeds. This is something most of us forget to do, but you can actually improve your gas mileage up to15 percent by driving at 55 mph rather than 65 mph.

Use your overdrive. If your car is equipped with overdrive gearing use it as soon as your speed is high enough.

Take advantage of the cruise control feature. Maintaining a constant speed will improve your gas mileage.

Improve the spark to your engine by changing your spark plugs. This way, the air and fuel mixture will  burn more efficiently for better gas mileage.

Improve your intake/output system. Helping gas get in and exhaust out of your vehicle will improve overall performance and gas mileage.

Reduce friction. Use high-quality or synthetic motor oil.

Check your oil! Low oil levels make your engine work harder.

Change your filters. Dirty filters can increase the amount of fuel your vehicle uses by up to 10 percent.

Get regular engine tune-ups and car maintenance checks. A lot can go wrong with a car. Damaged spark plugs or transmission problems can also contribute to poor gas mileage