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Keeping Your Car In Shape

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Oct. 07, 2009

Keep Your Engine Properly Tuned

Getting a tune-upFixing a car that is noticeably out of tune or has failed an emissions test can improve its gas mileage by an average of 4 percent, though results vary based on the kind of repair and how well it is done.

Fixing a serious maintenance problem, such as a faulty oxygen sensor, can improve your mileage by as much as 40 percent.
  Fuel Economy Benefit:
4%
  Equivalent Gasoline Savings:
$0.10/gallon

Keep Tires Properly Inflated

Sample tire pressure labelYou can improve your gas mileage by around 3.3 percent by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by 0.3 percent for every 1 psi drop in pressure of all four tires. Properly inflated tires are safer and last longer.

The proper tire pressure for your vehicle is usually found on a sticker in the driver's side door jamb or the glove box and in your owner's manual. Do not use the maximum pressure printed on the tire's sidewall.

Fuel Economy Benefit:
up to 3%

Equivalent Gasoline Savings:
up to $0.08/gallon

Use the Recommended Grade of Motor Oil
API energy conservation labelYou can improve your gas mileage by 1-2 percent by using the manufacturer's recommended grade of motor oil. For example, using 10W-30 motor oil in an engine designed to use 5W-30 can lower your gas mileage by 1-2 percent. Using 5W-30 in an engine designed for 5W-20 can lower your gas mileage by 1-1.5 percent. Also, look for motor oil that says "Energy Conserving" on the API performance symbol to be sure it contains friction-reducing additives.

Fuel Economy Benefit:
1-2%

Equivalent Gasoline Savings:
$0.03-$0.05/gallon


NEW INFORMATION:
Replacing a Clogged Air Filter on Modern Cars Improves Performance but Not MPG

Air FilterA new study shows that replacing a clogged air filter on cars with fuel-injected, computer-controlled gasoline engines does not improve fuel economy but it can improve acceleration time by around 6 to 11 percent. This kind of engine is prevalent on most gasoline cars manufactured from the early 1980s onward.

Tests suggest that replacing a clogged air filter on an older car with a carbureted engine may improve fuel economy 2 to 6 percent under normal replacement conditions or up to 14 percent if the filter is so clogged that it significantly affects drivability.

The effect of a clogged air filter on diesel vehicles will be tested in the near future.

Note: Cost savings are based on an assumed fuel price of $2.58/gallon.


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