Stretch Your Gas, Mile for Mile

Driving's always been the cheapest way to travel, the most flexible, and the best way to see the sights between Points A and B. Not to mention that it's the only way to get to some places. Too bad that now it sometimes seems like a luxury. Here are seven things you can do to make the road trip cheaper.

-- Margaret Roth

1. Stay in tune. There's nothing too exciting about routine maintenance, hence the "routine." But fuel policy wonks have proven it saves gas. The U.S. Department of Energy and the Environmental Protection Agency -- which bring you the Fuel Economy Guide and other money-saving info at http://www.fueleconomy.gov/ and http://www.epa.gov/otaq/consumer.htm -- have figured out how much. Fixing a faulty oxygen sensor, for example, can improve mileage as much as 40 percent -- think of it as getting $1.20 back on a $3 gallon of gas. Most maintenance items aren't that dramatic, a few percent saved here and there, but they add up.

Using that $3 gallon of gas to calculate potential savings, your checklist should include the car's air filter (saving 30 cents per gallon), emissions system (12 cents), tire pressure (10 cents) and motor oil (3 to 6 cents). The oil should match the manufacturer's recommended grade and carry the American Petroleum Institute's "energy conserving" label, meaning it contains friction-reducing additives. Regular wheel alignment and balancing can also help, as can tires designed with lower rolling resistance.

2. Use the trunk, minus the junk. The roof rack and luggage pods are a drag -- literally, cutting into your fuel economy by as much as 5 percent. The trunk is the aerodynamic, gas-saving place to haul your stuff, but you'll have to take out the unnecessaries first, especially in a smaller car where the extra weight makes a bigger difference. An extra 100 pounds cuts into mileage, if only by 1 to 2 percent.

3. Pick your pump wisely. There's always a cheaper option, and lots of ways to find it on the Web. Plan ahead and compare prices by the Zip code where you'll be filling up, at: GasBuddy.com ( http://www.gasbuddy.com/ ); AAA's Fuel Price Finder ( http://www.aaamidatlantic.com/fuel_finder.asp ); GasPriceWatch .com ( http://www.gaspricewatch.com/ ); Automotive.com ( http://www.automotive.com/gas-prices ); or MSN Autos ( http://autos.msn.com/everyday/gasstations.aspx ). If you're returning a rental car, Expedia's gas station locator ( http://www.expedia.com/cars ) searches by airport code.

4. Hold down the octane. If the manufacturer recommends regular unleaded, that's what you should use. Going higher won't turn your Kia into a Corvette. Nor, chances are, will fuel additives and other devices advertised as improving mileage or emissions, according to the Federal Trade Commission ( http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm ).

5. Steer clear of traffic. Idling is bad. Cruise control is good. It's a smart idea to plan your route around traffic so you can keep up a steady speed. Many state highway departments have Web sites that provide up-to-date info on construction and other backups. Maryland's is http://www.chart.state.md.us/travinfo/travinfo.asp ; Virginia's is http://www.virginiadot.org/comtravel/default.asp . Assuming traffic is flowing everywhere (obviously not near D.C.), head for the highway. Tom Symons of Pottsville, Pa., in response to a query on OBX Connection ( http://www.obxconnection.com/ ), a Web site geared to Outer Banks travelers, said he has found it worthwhile to head south on Interstate 81 toward I-64 in Virginia instead of U.S. 15 farther east, with cruise control set at 65. "I'm bypassing the smaller roads with the towns and red lights," he said.

6. Back off. Aggressive driving and speeding are the top two ways to waste gas, says David Greene of Oak Ridge National Laboratory's Center for Transportation Analysis in Knoxville, Tenn. Greene, an analyst who contributes to the Fuel Economy Guide, says: "If you are an aggressive driver, accelerate rapidly and darting in and out of lanes, always looking to pass, you're probably wasting anywhere from 10 to 30 percent of your fuel," more at highway speeds than around town.

"Speeding is another thing," Greene says. Gas mileage usually plummets at speeds over 60 mph, according to the Fuel Economy Guide. Many cars have mileage gauges built in to the dashboard so you can see the effects of your driving. That means every 5 mph you drive over 60 is costing you about a quarter a gallon for gas. Basically, accelerating sucks fuel.

And, if you have overdrive gears, use them. It slows down your engine speed, which saves on gas consumption.

7. Watch your gas mileage. Cars are as variable as the people in them. Keep an eye on how you're driving and using gas, and you can save all the time, not just on vacation.

"We need to challenge people to consciously change their driving habits," says Wendy Dafoe, an information analyst with the Energy Department's National Renewable Energy Lab. "I've long thought that people just need to write it down and see for themselves." Pack a notepad and a calculator; you may be surprised at the difference your driving can make.