7 Most Common Gas-Guzzling Mistakes

Did you know that for every 5 mph you drive over 50 mph, you're paying an extra 26¢ per gallon for gas? It's easier than you think to avoid common mishaps like this—and save money at the pump.

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With the national average price of gas nearing $4 a gallon, drivers are feeling the sting, but there's no need to cancel your vacation. We sifted through mounds of data from the government, automotive consumer advocates, and car rental agencies to find out how to squeeze every last penny out of what you put in your tank. Here is what you need to know before your next summer driving adventure.

The Mistake: Driving Too Fast

Why it matters: While each car reaches its optimal fuel economy at different speeds, gas mileage typically decreases rapidly at speeds above 50 mph. For every 5 mph you drive over 50 mph, you're paying an extra 26¢ per gallon for gas, according to, the official U.S. government source for information on energy efficiency. Plus gas is consumed faster when accelerating hard.

What to do: Try not to drive faster than the speed limit when on the highway. When around town or in traffic, avoid jackrabbit starts; accelerating gently can improve your gas mileage by up to 5 percent in town and 33 percent on the highway, according to If using a manual car, use overdrive gears whenever possible to reduce engine speed (and gas use). It's really about how smoothly you drive, so use cruise control whenever possible to maintain a steady speed.

The Mistake: The Air Conditioner Is Used Improperly

Why it matters: Should the air conditioner be on or off? Many experts say it depends on your speed. When driving at slower speeds—say, around town—turn off the air conditioner and roll down the windows because the engine has to work harder to pump out cool air. According to Ford Motor Company's Driving Skills for Life program, at speeds above 50 mph close the windows and use the air-conditioning—at highway speeds, open windows increase the aerodynamic drag and the engine actually works harder than if it were using the A/C. However, when the Discovery Channel's Emmy-nominated TV series MythBusters tested this theory, they concluded the air conditioner should be avoided no matter the speed. came to a similar conclusion when it tested a Honda Accord—the effect of opening the windows at 65 mph was not measurable, whereas using the air conditioner did reduce gas mileage by over 3 mpg.

What to do: When driving around town or at slower speeds, abstain from using the air conditioner. When on the highway, we recommend avoiding the A/C. If you need cool air, use the vent setting instead. It also helps to park the car in the shade to keep it cool and reduce the need for air-conditioning. If you must use the A/C, first open the windows to remove the hot air before turning it on—by doing so you will reduce fuel consumption, according to the Green Driving Tips on

The Mistake: Too Much Luggage on (And in) the Car

Why it matters: A loaded roof rack can increase wind resistance, diminish the aerodynamics of the car, and decrease fuel economy by 2 percent. Similarly, extra luggage in the trunk weighs down the car and requires more work (and more gas) from the engine—an extra 100 lbs in the trunk reduces a typical car's fuel economy by 1 to 2 percent or about 4¢ to 8¢ a gallon, according to

What to do: Remove and store the luggage racks, bike racks, ski racks, and kayak holders until you absolutely need them, or try to put some of those items in the trunk instead. And, of course, pack less! (It is possible, with the right techniques, to fit everything you need for two people traveling for a weekend into one carry-on.)

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Note:This story was accurate when it was published. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.

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