You don't have to buy a Prius, trade in your clunker or ride the bus to cut down on the money you spend for gas each month. Just make a few adjustments to your driving habits:

Drive sensibly. Aggressive driving on the highway -- speeding, rapid acceleration and braking -- can lower your mileage by 33%.

Observe the speed limit. Gas mileage decreases rapidly above 60 miles per hour. Reining in your speed will save you up to 23%.

Keep tires inflated properly. Check your owner's manual to list your vehicle's proper tire pressure, buy a good dial-type pressure gauge ($8), and check your tires once a week. Keeping them properly inflated can improve your mileage by about 3%.

Empty the trunk. Don't carry around unnecessary items, especially in small cars. An extra 100 pounds in your vehicle could reduce your miles-per-gallon by up to 2%.