Whether you are shopping for a new car or just trying to maintain the one you have, you can take some steps to get the best mileage out of your gas purchases. Regardless of the make and model, your car’s estimated gas mileage is just that — an estimate. An important variable is how you fuel, drive, and maintain your car. The Federal Trade Commission (FTC), the nation’s consumer protection agency, offers these tips to use fuel efficiently:

The Gas Tank: Use the Octane Level You Need

Making the right choice at the gas pump is an important first step to keeping your car running efficiently — and economically. Follow your owner’s manual recommendation for the right octane level for your car. For most cars, the recommended gas is regular octane. Using a higher octane gas than the manufacturer recommends offers no benefit — and costs you at the pump. Unless your engine is knocking, buying higher octane gas is a waste of money. Be sure to tighten your gas cap after each fill up.

How important are vehicle gas caps?
17 percent of the vehicles on U.S. highways have either misused or missing gas caps, causing 147,000,000 gallons of gas per year to vaporize into the atmosphere. (Source: Service Tech Magazine, Sept. 2000)

Vehicle conditions that cost consumers millions of dollars in wasted fuel:

• Loose or missing gas caps
• Underinflated tires
• Faulty thermostats
• Worn spark plugs
• Malfunctioning engine controls
• Poor wheel alignment

On the Road: Drive More Efficiently

• Stay within posted speed limits. Gas mileage decreases rapidly at speeds above 60 miles per hour.
• Stop aggressive driving. You can improve your gas mileage up to five percent around town if you avoid “jackrabbit” starts and stops by anticipating traffic conditions and driving gently.
• Avoid unnecessary idling. It wastes fuel, costs you money, and pollutes the air. Turn off the engine if you anticipate a wait.
• Combine errands. Several short trips taken from a cold start can use twice as much fuel as one trip covering the same distance when the engine is warm.
• Use overdrive gears and cruise control when appropriate. They improve the fuel economy of your car when you’re driving on a highway.
• Remove excess weight from the trunk. An extra 100 pounds in the trunk can reduce a typical car’s fuel economy by up to two percent.
• Avoid packing items on top of your car. A loaded roof rack or carrier creates wind resistance and can decrease fuel economy by five percent.

At the Garage: Maintain Your Car

• Keep your engine tuned. Tuning your engine according to your owner’s manual can increase gas mileage by an average of four percent. Increases vary depending on a car’s condition.
• Keep your tires properly inflated and aligned. It can increase gas mileage up to three percent.
• Change your oil. According to the U.S. Department of Energy (DOE) and Environmental Protection Agency (EPA), you can improve your gas mileage by using the manufacturer’s recommended grade of motor oil. Motor oil that says “Energy Conserving” on the performance symbol of the American Petroleum Institute contains friction-reducing additives that can improve fuel economy.
• Check and replace air filters regularly. Replacing clogged filters can increase gas mileage up to ten percent.

How do underinflated tires affect fuel efficiency?
Underinflated tires and incorrect wheel alignment can lead to conditions which increase rolling resistance. This is like driving with the parking brake not fully released, it can cost a mile or two per gallon on a car that normally delivers 20 miles per gallon. Correct tire inflation pressure is critical for good fuel economy, safety, maximum tire life and proper vehicle handling performance.

Other gas guzzlers include:

• Dirty oil = 1 mile per gallon
• Slipping automatic transmission = 1 mile per gallon
• Cooling system thermostat that causes the engine to run too cold = 2 miles per gallon