1. Find a bargain.
If you're taking a summer road trip, plan out your route before you go. Identify gas stations along the way that have the lowest prices.
When I stopped in a beach town last week to fill up my car I didn't plan like I should have (I almost ran out of gas), and it cost me the most I'd ever paid for gas -- $3.85 a gallon. Next time I'll go to GasBuddy.com, a site that lets consumers share gas price information easily, and find a better deal before I head for the beach.
2. Keep your tires fully inflated.
The U.S. Department of Energy reports that the average driver can improve mileage by 3.3 percent simply by inflating their vehicle's tires regularly.
In fact, according to the AAA, under-inflated tires are the No. 1 way we waste gas. One out of every four cars and one out of every three pickups, vans, and SUVs have at least one extremely low tire. So pick up a tire gauge at your local auto parts store and check your tire pressure whenever you pull into a service station for gas. Your car's owner's manual will tell you the recommended PSI -- pounds per square inch -- rating.
3. Get a tune-up.
A vehicle in need of servicing is wasting gas in more ways than one. According to the Department of Energy, replacing a clogged air filter can improve your gas mileage by 10 percent, while fixing a faulty oxygen sensor can improve gas mileage by an unbelievable 40 percent.
So kick off your summer by getting that tune-up you've been putting off. Check your owner's manual, or download a free service and maintenance schedule at CarCare.org.
4. Fill 'er up with regular unleaded if possible.
If premium gas isn't absolutely required by your car's manufacturer, then opt for regular unleaded. According to AAA, one out of five gallons of gas pumped in the U.S. is premium -- yet only 10 percent of vehicles require this higher octane fuel.
The truth is that you may not even notice the difference when you drive your car with regular gas instead of premium, and the cost difference can be as much as 40 cents per gallon. If your car doesn't require premium unleaded, you're wasting your money -- premium doesn't improve performance.
5. Adjust your driving habits.
Speeding, excessive accelerating, and sudden braking all waste gas. A more relaxed driving style not only improves safety, it also improves gas mileage by 33 percent for highway driving.
Idling your engine for long periods can also waste up to a gallon of gas per hour. Also, think twice before blasting the air conditioning. According to the Department of Energy, operating your car's air conditioner on its maximum setting can reduce your miles per gallon by 5 to 25 percent compared to not using it at all.
6. Clean out your trunk.
Unnecessary cargo weighs your car down. A hundred extra pounds can reduce your miles per gallon by 2 percent.
Going on vacation? Try to avoid storing luggage on your roof. The increased wind resistance will reduce your mileage as well.
You'll literally save thousands of dollars a year in fuel costs if you share a ride to work. Here's an example: If you commute to work 40 miles per day round trip, work full-time, drive a vehicle that gets 24 mpg, and pay the national average for gas, your estimated yearly cost to commute is $5,124.
But if you carpool with one other person, you'll save an estimated $2,562 a year. Carpool with three other people and you'll save an estimated $3,843 a year.
Plug your own commuting numbers into the CommuteSmart cost calculator to see what you can save by carpooling. Then find a rideshare buddy in your area by visiting eRideShare.com.
8. If you're buying a new car, make fuel efficiency a priority.
There's so much to consider when purchasing a new car that fuel efficiency can get lost in the shuffle. By law, however, the Environmental Protection Agency's (EPA) fuel efficiency rating for new cars is posted in large black numbers on a sticker in the window.
Due to the way vehicles (including hybrids) are tested, those EPA ratings didn't used to reflect real-life conditions. But according to a recent Consumer Reports article, the EPA is using a more accurate method for determining fuel efficiency for all 2008 vehicles. So whether you're shopping at a dealer or comparing EPA estimates online, some quick calculations will help you find a fuel efficient car that's right for you.
9. Buy a hybrid, get a tax break.
Driving a hybrid, which runs on a combination of gas and electric power, will significantly increase your miles per gallon. Hybrid cars are becoming more affordable, too.
According to a recent Wall Street Journal article, in the past it took up to 15 years for the cost savings on gas to offset hybrids' higher sticker prices. But now buyers are seeing a significantly shorter length of time to recoup their investment -- for some models, the break-even period is less than a year.
The government is even offering tax incentives when you purchase certain hybrid vehicles.