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12 Things to Do Now to Improve Gas Mileage

The savings are based on driving 20,000 miles per year, in a car that gets 20 mpg, with gasoline priced at $3.75 a gallon.

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hand and car wheel add air pressurecunaplus/Shutterstock

Save $900 by keeping your tires at the right pressure

Surveys show that 60 percent of the vehicles on the road have tires that are underinflated by at least 30 percent. That’s at least 9 psi below the manufacturer’s recommended pressure. That can cost you almost 7 percent in wasted fuel ($245 per year, or 24¢ per gallon). Plus, low air pressure causes premature tire wear, and that can cost almost $300 over the life of the tires. For best results, check your tire’s air pressure with a digital pressure gauge and fill to the recommended pressure shown on the decal inside the driver’s door or on the driver’s door pillar. Still, it would be nice if a built-in pressure gauge was one of the weird car features you didn’t know you had.

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check engine air filterFamily Handyman

Replace your air filter often

Your engine sucks in 14 million gallons of air through the filter every year. On older vehicles (pre-1999) a dirty air filter increases fuel usage by almost 10 percent ($350 per year, or 35¢ per gallon). On newer vehicles, the computer is smart enough to detect the lower airflow, and it cuts back on fuel. So your engine will lack power and pick-up. Check the filter when you change your oil and replace it at least once a year, or more if you drive in dirty, dusty conditions.

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Family Handyman

Replace spark plugs early and save a lot

If your 100,000-mile spark plugs have 80,000 miles on them, they’re 80 percent worn. Misfires and incomplete combustion occur more frequently during that last 20,000 miles, costing you almost $562.50 in wasted fuel. You have to replace your spark plugs anyway, so do it early and pocket the savings. Even if you have to replace the plugs one extra time over the life of your car, you’ll still come out way ahead. And don’t automatically assume your plugs are good for 100,000 miles. Many four-cylinder engines require new spark plugs at either 30,000- or 60,000-mile intervals. Look out for these other 15 suggested car repairs by car mileage.

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Auto wheel alignment in auto service, SUV maintenance. Car preparing for professional diagnosticsGolubovy/Shutterstock

Save $177.50 by keeping your car aligned

If your tires are bowed out of alignment by just .017 in., it’s the equivalent of dragging your tire sideways for 102 miles for every 20,000 you drive. That’ll cost you $187.50 a year in wasted gas. It will wear your tires faster, costing you $70 more a year.

Here’s an easy way to check your alignment without taking your car in to the shop. Buy a tread depth gauge and measure the tread depth on both edges of each tire (rear tires too). If one side of the tire is worn more than the other, your car needs to be aligned. An alignment costs about $80, so you’ll still save $177.50 the first year alone.

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Hand a man with Car thermostat for maintenanceNONGASIMO/Shutterstock

Replace a failing thermostat

A thermostat that opens too quickly or stays open can dramatically lower the coolant temperature and put a mega-chill on your gas mileage. All you need to check it is an inexpensive infrared laser thermometer. Simply aim it at the thermostat housing. If your engine is warmed up and the thermometer reads less than 160 degrees Fahrenheit, you’re wasting gas and it’s time to replace the thermostat. (To reduce reflection errors, spray the thermostat housing with black paint prior to testing.) A new thermostat costs about $10 and is easy to replace.

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Close up Leather Shoe ob pedal in carJimAK_Photo/Shutterstock

Save money by driving slower

Hard acceleration in stop-and-go driving costs you 20 percent in gas mileage. If you live your life in rush hour traffic and like to put the pedal to the metal, spend all your extra time at the next stoplight figuring out how you could have spent the $750 a year you’re wasting (70¢ per gallon). Plus, it’s safer! Here are 10 scary driving scenarios and exactly how to handle them.

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White sign with "speed limit 55" printed in black. Sign is shot against a blue sky. PHOTO ID: SpeedLimit5500016Tom Fawls/Shutterstock

Drive 55

Speed kills your gas mileage and your wallet. Yes, you’ve heard it before, but how about some real-world numbers to, ahem, drive the point home? Aerodynamic drag is a minor concern in city driving, but it really kills your gas mileage at speeds over 55 mph. In fact, increasing your speed to 65 increases drag by 36 percent! If you do a lot of highway driving, getting to your destination a few minutes early could cost you an extra $510 a year. Keep it closer to 55 mph and use your cruise control. It will pay off.
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oxygen sensorFamily Handyman

Replace your oxygen sensor(s) before the light goes on

Oxygen sensors monitor the efficiency of combustion by tracking the amount of oxygen remaining in the exhaust. But they degrade over time and that can cost you up to 15 percent in gas mileage. When they fail, the computer lights up your ‘service engine soon’ light, forcing you to incur an $80 diagnostic fee. On pre-1996 vehicles, replace your oxygen sensor every 60,000 miles to keep your mileage at its peak. On 1996 and newer vehicles, replace the sensors every 100,000 miles. Oxygen sensors cost about $60 each. Some vehicles have as many as four, but the sensors installed behind the catalytic converter rarely fail.

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spoiler-splash-guardFamily Handyman

An air dam (spoiler) reduces fuel costs

The plastic air dam (aka “spoiler”) that’s broken or missing wasn’t just for a sporty look. If your car had an air dam, driving without it or with a damaged one can reduce your gas mileage. The air dam literally “dams off” airflow to the undercarriage of your car, forcing the air up and over the hood. That helps your car cut through the air with less drag. It also increases airflow to the A/C condenser and radiator, reducing the load on your car’s electrical system. Contact a junkyard or visit to get a replacement air dam. But that’s not the only genius way to save on gas.

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Car Brake Part at Garagekpakook/Shutterstock

Check for brake drag

Brake drag can really sink your mileage. Brake calipers have a nasty habit of rusting, binding and dragging down your gas mileage. How can you tell if your brakes are dragging without having them checked at a shop? Easy! Buy an inexpensive noncontact infrared laser thermometer (about $20 at any home center), remove the wheel cover (if equipped), and aim the laser at the wheel hub after a drive. Compare the readings from the right and left sides. If they vary by more than 20 percent, you’ve probably got a dragging brake or a wheel bearing problem, so take it in for repairs.

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Replace Your Cabin Air FilterFamily Handyman

Replace your cabin air filter

A clogged cabin air filter can damage your car’s blower motor and cause your AC to run longer and harder in the summer. Cabin air filters are easy to access and replace and you’ll save about $30 by doing it yourself. Buy a replacement cabin air filter at any auto parts store and ask the clerk to print out the installation instructions. Cabin air filters are usually located in the air ducts behind the glove box in late model vehicles. However, some car makers locate them in the cowling or console area. Just remove the access covers and slide out the old filter. Note the direction of the airflow arrows so you can install the new filter in the proper orientation. Then reinstall the covers and you’re done.
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Car dashboard warning lights. Engine start moment. System check. Hybrid car.vpilkauskas/Shutterstock

Keep an eye on warning lights

Pay attention to your warning lights. Car owners think a glowing check engine light isn’t important because it just means you’ve got an “emissions problem.” Guess what? Emissions problems are almost always caused by an incomplete burn and that means you’re not getting the most bang for your buck. In other words, a check light means you’re wasting gas. Worse yet, all that extra gas goes right into your expensive catalytic converter, causing it to fail early. A new catalytic converter can run upwards of $1,000 to replace and then you STILL have to fix the underlying problem that turned on the check engine light in the first place. Many times the check engine light comes on due to a bum sensor or vacuum leak. Replacing a sensor or fixing a vacuum leak can save far more than what you’ll waste in reduced MPG. The most well-known light on the dash, here’s what to do if your brake light comes on.

The Family Handyman
Originally Published on The Family Handyman