Great Tips for Getting Better Gas Mileage

Keep your tires inflated to the recommended pressure. Surveys show that 50 percent of all drivers' tires are underinflated. You can't 'eyeball' tire pressure and you shouldn't rely on the low tire pressure warning light--it only lights up when your tires are at least 25% underinflated. At that point you've already started wasting gas. Instead, check them monthly with a tire pressure gauge (less than $5). Underinflated tires have higher rolling resistance, causing your engine to work harder and waste almost $600 a year in gas. Low air pressure also wears out your tires twice as fast, costing you an additional $150 a year. The recommended air pressure for your vehicle's tires is on the decal pasted to the driver's door or pillar. Learn how to make your tires last longer here.

Change your spark plugs BEFORE they're due. Most drivers think their spark plugs last well over 100K miles. That's true for some engines, but not all. In fact, if you own a car with a turbocharger, chances are you should be replacing your spark plugs every 30,000 miles. Refer to your car's maintenance guide for the recommended interval for your particular engine. Even then, it's never a good idea to squeeze the last drop of life out of your spark plugs. Here's why. 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 $450 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. Figure out what to look for when buying spark plugs and get the full how-to on changing spark plugs here.

Keep your car aligned and save about $140 per year. 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 $150 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 ($2) 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 $140 the first year alone. Learn more about tires here.

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. Learn how to replace your car thermostat here and save gas money.

Lighten up on the heavy acceleration dude because a lead foot = a light wallet. You don't really want us to recite the law of physics about how a body at rest tends to stay at rest, do you? OK, we'll just skip to the part about how 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, here's our advice: Spend all your extra time at the next stoplight figuring out how you could have spent the $600 a year you're wasting.

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. Next time you need to bring in your car for brake repairs, know the common ripoffs at repair shops.

Replace a broken or missing spoiler and under-engine splash guards. The plastic air dam (aka "spoiler") that's broken or missing wasn't just for looks. It actually served a purpose; it forces air up and over the hood to help your car cut through the air with less drag. The under-engine splash guards help reduce aerodynamic drag too by keeping the air flowing smoothly under your car instead of producing turbulence that causes drag. Contact a junkyard to find a replacement air dam and engine splash guards.

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. You know what else will pay off, these 36 car detailing tips the pros don't want you to know.

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. Stop thinking those warning lights are hieroglyphs and learn how to decipher them.

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. It's one of at least 100 car maintenance tasks you can do on your own. 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. See how to remove and replace your cabin air filter here.