• Slow down! Yup, we've all heard it, but now we should all do it! Since fuel economy drops rapidly over 65 mph, make sure you don't rest your foot too heavily on the gas pedal.
• Keep your speed steady. Lots of quick starts and stops use more fuel than maintaining a consistent speed. So on the highway, use your cruise control (except on hilly areas, where you can save more gas by picking up speed as you coast downhill and slowing down a bit as you head uphill). And in town, watch the cars and traffic lights well ahead of you so you don't need to slam on the brakes quickly.
• Keep your tires inflated properly. Your car manual and the tires themselves will tell you what pressure level is appropriate.
• Lighten your load. It takes more fuel to move a heavier car around, so if you still have that bag of sand in the trunk to help out with winter ice, and you have an unused luggage rack on the roof, it is time to remove them. Remember that even the little things add up, so remember to keep your car cleaned out!
• Let the breeze blow. At speeds of less than 60 mph, you'll save gas by cooling off with a breeze from an open window; at 60 mph and above, it is better to use your car's air conditioning system.
• No more circling. Can't find the perfect parking spot? Quickly settle for second (or third, or fourth) best rather than wasting fuel driving around the lot. And as an added bonus, a bit more of a walk will help your waistline as well as your wallet.
• Keep Clean. Clean the air filter monthly to keep your engine running efficiently.
• Don't Idle. If you are stopping for more than a minute, it uses less gas to turn off the engine and start it up again than to leave it idling (of course this doesn't apply in traffic or at stoplights). Similarly, "warming up" your car just wastes fuel, except during winter in the coldest of climates.

On Vacation

• Don't get lost. Use a GPS device to ensure that you're always on the right route so you don't spend extra miles out of your way.
• Tune in to technology. Use web sites like those from traffic.com and the Federal Highway Administration to avoid detours and traffic tie-ups that would otherwise cost you extra time and fuel.

Web Resources

• Find the gas station with the lowest price in your neighborhood at GasPriceWatch.com and GasBuddy.com.
• More resources for finding cheaper gas are at MSN.com.
• Look for credit cards that offer rebates for gas purchases at BestCreditOffers.com and inns that are reimbursing you for your gas expenses at About.com.

Above all, you need to plan every car trip like the investment it is. If you can just as easily accomplish your goal by walking or biking or using public transportation, it almost goes without saying that that's what you should do. But if you truly need your vehicle, think about mapping out each stop in a careful, organized fashion so that you drive as little as possible.