Keeping Your Vehicle in Shape
Fixing a car that is noticeably out of tune or has failed an emissions test can improve its gas mileage by an average of 4%, 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%.1
Fuel Economy Benefit: | 4% |
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Equivalent Gasoline Savings: | $0.09/gallon |
Updated Information
You can improve your gas mileage by 0.6% on average—up to 3% in some cases—by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by about 0.2% for every 1 psi drop in the average pressure of all tires. Properly inflated tires are safer and last longer.2
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: | 0.6% |
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Equivalent Gasoline Savings: | $0.01/gallon |
You can improve your gas mileage by 1%–2% 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%. Using 5W-30 in an engine designed for 5W-20 can lower your gas mileage by 1%–1.5%. Also, look for motor oil that says "Energy Conserving" on the API performance symbol to be sure it contains friction-reducing additives.1
Fuel Economy Benefit: | 1%–2% |
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Equivalent Gasoline Savings: | $0.02–$0.04/gallon |
Replacing a clogged air filter on vehicles with fuel-injected, computer-controlled gasoline engines—such as those manufactured from the early 1980s to the present—or diesel engines does not improve fuel economy, but it can improve acceleration.
Replacing a clogged air filter on an older vehicle with a carbureted engine can improve both fuel economy and acceleration by a few percent under normal replacement conditions.3, 4, 5
- Estimates for fuel savings from vehicle maintenance and using the recommended grade of motor oil based on Energy and Environmental Analysis, Inc., Owner Related Fuel Economy Improvements, Arlington, Virginia, 2001.
- Revised June 27, 2016. Estimates for fuel economy improvement from properly inflating tires assume a vehicle with an average under-inflation rate of 10% across all tires (25% for worst-case tire inflation scenarios). The rolling resistance sensitivity to tire pressure and the return factor (the ratio of the percentage improvement in fuel economy to a percentage reduction in rolling resistance) are taken from The Pneumatic Tire (NHTSA 2006).
- NHTSA. 2012. Evaluation of the Effectiveness Of TPMS in Proper Tire Pressure Maintenance. Figure 8, p. 28.
- NHTSA. 2006. The Pneumatic Tire. DOT HS 810 561. Chapter 12, Rolling Resistance, pp. 475-532.
- Thomas, J., West, B., Huff, S. 2013. Effect of Air Filter Condition on Diesel Vehicle Fuel Economy. SAE Technical Paper 2013-01-0311.
- Thomas, J., West, B., Huff, S., and Norman, K. 2012. Effect of Intake Air Filter Condition on Light-Duty Gasoline Vehicles. SAE Technical Paper 2012-01-1717.
- Norman, K., Huff, S., and West, B. 2009. Effect of Intake Air Filter Condition on Vehicle Fuel Economy. ORNL/TM-2009/021. Oak Ridge National Laboratory.