NEW YORK (CNNMoney.com) - You can get 35 percent better fuel mileage out of your current vehicle by using a device most drivers already have.

That would be your right foot.

Most drivers agonizing over the cost of gasoline fail to realize the enormous impact their driving style has on fuel consumption.

During the last run-up in fuel prices, we wrote about Edmunds.com's tests of common fuel-saving driving tips. Some common tips, it turned out, had little or no effect on fuel economy. (Edmunds.com provides data and content for CNN.com's automotive Websites.)

For example, using the air conditioner at highway speeds had no appreciable effect on fuel economy compared to rolling down the windows.

Keeping your tires properly inflated, while important for safety, has only a small effect on fuel mileage, according to Edmunds.com's tests.

Using cruise control on the highway, though, really does have a noticeable effect on fuel economy. In Edmunds.com's test using a Land Rover LR3 and a Ford Mustang, the Land Rover got almost 14 percent better mileage using cruise control set at 70 miles per hour rather than cruising at driver-controlled speeds between 65 and 75 miles per hour. The Mustang got 4.5 percent better mileage.

Using cruise control cuts down on unnecessary speed changes which can eat up gas and it prevents "speed creep." the tendency for a driver's average speed to gradually increase with time spent on the road. (In that way, it can save you from an expensive speeding ticket, as well.)

If you want a big gain in fuel mileage, though, you need to seriously lay off the pedals when driving around town. Accelerating more slowly away from green lights and stopping more gradually for red lights cut fuel consumption in Edmunds.com's tests by 35.4 percent for the Land Rover and 27.1 percent for the Mustang.

Slamming down the gas pedal pushes more fuel into the engine while it also keeps the engine running faster.

You can also save a lot of gas by just lifting your foot off the accelerator as soon as possible when approaching a yellow or red light or a stop sign.

For one thing, letting up on the gas sooner gives your car more coasting time.

By the way, when we say "accelerating hard" and "stopping abruptly" we aren't necessarily talking about juvenile tire-squealing antics. If you start keeping a conscious eye on how you drive, you may realize that you've been hot-rodding around for years without realizing it.

In Edmunds.com's tests, they slowed acceleration times down to a 20-second run from zero to sixty miles per hour. Compared to the kind of zero-to-sixty times we hear car makers bragging about these days, 20 seconds may sound impossibly slow. In fact, it is slow. But, while it won't get your pulse pounding, it will get you safely onto the highway.

Since most drivers don't have a stopwatch handy to time their acceleration, Cole Quinnel, a spokesman for Chrysler Corp. engineers, advises not pressing the gas pedal down by more than an inch unless you really have to. Using that approach, the difference in fuel economy will be appreciable.

Let's say that your car currently gets 22 miles per gallon overall. If this laid-back driving style gets you just 30 percent more in fuel mileage, which Edmunds.com's tests indicate it could, you'd see that increase to about 30 miles per gallon.

It's not easy, though. For most people, driving this way will feel, to say the least, awkward. When I tried Quinnel's high-mileage driving advice, it was difficult to maintain this disciplined approach to acceleration and deceleration without consistent effort. The minute I let my concentration slip -- Zoom! -- off I'd go again in a gas-wasting rush, just like I usually do.

And, to be perfectly honest, it was a little embarrassing to drive that way. Every molecule of testosterone in my body was begging to be excused for the day.

But, in a couple of short drives, the car was using significantly less gas per mile, even with my occasional slip-up. Maybe if I keep it up, I can soothe my dented ego with a little cash in my wallet.

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• How 'Xtreme Savers' save on gas
• Gas saving tips put to the test
• How to shop for a fuel-efficient car

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