How to Improve Your Gas Mileage: 15 Tested Tips

Most of the fuel your car burns is decided by how you drive, not by additives or gadgets. The tips below are drawn from testing published by the US Department of Energy and EPA on fueleconomy.gov (opens in a new tab), plus basic maintenance that keeps an engine running as efficiently as it was designed to. They are ordered roughly from biggest effect to smallest. Before you start, measure your baseline MPG so you can see what actually changes.

You cannot improve what you do not measure, and the dashboard MPG readout can be optimistic by a few percent.

1. 1Fill the tank until the pump clicks off, and zero a trip odometer.
2. 2Drive normally until you need fuel again.
3. 3Fill up the same way, ideally at the same pump, and note the gallons.
4. 4Divide miles driven by gallons added.

Repeat over three or four tanks for a stable average. Our MPG calculator does the math and tracks the trend, and logging fill-ups in a free garage keeps the history in one place.

1. Drive smoothly

Hard acceleration and late braking waste fuel that you paid to turn into speed. According to fueleconomy.gov, aggressive driving can lower gas mileage by roughly 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic. Accelerate gently, look well ahead, and lift off early when you see a red light.

2. Slow down on the highway

Aerodynamic drag rises steeply with speed, so fuel economy usually drops quickly above about 50 mph. The exact peak varies by vehicle, but dropping from 75 to 65 mph is one of the most reliable savings on a road trip. It also adds only a few minutes per hour driven.

3. Use cruise control on open, flat roads

Cruise control holds a steady speed and avoids the small, constant speed changes most drivers make. On hilly roads it can be less efficient because it accelerates hard to hold speed uphill; there, let speed drop slightly on climbs and recover on descents.

4. Cut unnecessary idling

An idling engine gets zero miles per gallon. Fueleconomy.gov estimates idling can use a quarter to a half gallon of fuel per hour, depending on engine size and air conditioner use. If you will be parked more than a minute or so, turn the engine off (where safe and legal). Modern cars do not need long warm-ups; drive gently for the first few minutes instead.

5. Combine trips

A cold engine is less efficient than a warm one. Several short trips from a cold start use more fuel than one longer trip covering the same errands. Plan a loop, and do the farthest stop first so the engine warms up.

6. Use the right drive mode

Eco modes soften throttle response and change shift points, which helps drivers who tend to accelerate hard. Sport modes do the opposite. On a hybrid, gentle acceleration and long, gradual braking let the electric motor and regenerative braking do more of the work.

7. Remove roof racks and cargo boxes when not in use

A rooftop cargo box is one of the largest avoidable penalties. Fueleconomy.gov reports a large, blunt rooftop cargo box can reduce fuel economy by around 2% to 8% in city driving, 6% to 17% on the highway and 10% to 25% at interstate speeds. Empty crossbars cost less but still add drag. A rear-mounted hitch carrier has a much smaller effect.

8. Take out heavy items you do not need

Extra weight costs fuel mainly in stop-and-go driving. Fueleconomy.gov notes that an extra 100 pounds in a vehicle could reduce MPG by about 1%, with smaller vehicles affected more. Golf clubs, tool boxes and bags of sand left in the trunk all year add up.

9. Windows vs air conditioning

At low speeds, open windows usually cost less than the A/C. At highway speeds, open windows add drag, and using the A/C moderately is often the better choice. On very hot days, the A/C is one of the biggest loads on the engine, so use recirculate mode and avoid setting it colder than you need.

10. Keep tires at the right pressure

Use the pressure on the placard inside the driver's door jamb, not the maximum printed on the tire sidewall. Check monthly with the tires cold. Underinflated tires roll with more resistance and wear faster; fueleconomy.gov estimates keeping tires properly inflated can improve gas mileage by up to 3% in some cases. See how to check tire pressure and tread depth.

11. Use the recommended motor oil

Use the viscosity grade listed in your owner's manual (for example, 0W-20 or 5W-30). Heavier oil than specified can lower fuel economy slightly. Look for the API "Energy Conserving" mark if your manual calls for it. See synthetic vs conventional oil.

12. Fix check engine lights promptly

Several common faults quietly waste fuel: a lean or rich fuel mixture, a failing oxygen sensor or a misfire. If your MPG drops suddenly, scan for codes. Codes like P0171 (system too lean), P0300 (random misfire) and oxygen sensor codes such as P0133 often come with a mileage drop. Our check engine light guide covers what to do first.

13. Keep up with alignment and brakes

A misaligned car or a dragging brake caliper adds rolling resistance. Signs include the car pulling to one side, uneven tire wear, or one wheel noticeably hotter than the others after a drive.

14. Replace the engine air filter on schedule

On modern fuel-injected engines, a dirty air filter mainly reduces power and acceleration rather than MPG, but it is cheap to replace and part of normal maintenance. Check your owner's manual for the interval.

15. Buy the octane your car requires, not more

If your manual says regular (87 in most areas), premium fuel will not improve mileage or power in a typical engine. If it says premium is required, use it. If it says premium is recommended, regular is usually safe but may reduce performance and economy slightly. Our gas vs premium calculator shows what the difference costs over a year.

Skip these:

• Fuel-saving gadgets and additives. The EPA has tested many devices marketed as fuel savers and found that most did not measurably improve fuel economy. The FTC has also warned consumers about gas-saving product claims (opens in a new tab).
• Coasting in neutral. Modern fuel-injected engines cut fuel almost entirely when you lift off the gas in gear. Neutral keeps the engine idling, uses fuel, and reduces control.
• Overinflating tires. Going far above the placard pressure reduces grip and braking performance for a tiny MPG gain.
• Drafting behind trucks. Dangerous, and not worth any saving.
• Filling up in the morning because fuel is "denser". Fuel is stored underground at a fairly stable temperature, so the effect is negligible.

• Measure baseline MPG over three or four tanks.
• Check tire pressure monthly, cold, to the door placard.
• Remove the roof box and unused weight.
• Accelerate gently and anticipate stops.
• Drive 5–10 mph slower on the highway.
• Turn the engine off instead of idling.
• Combine short trips.
• Use the oil grade and octane in your manual.
• Scan any check engine light and fix it.
• Re-measure MPG after a month.

To see how your car's measured MPG compares with its official rating, look it up on our model research pages or read real-world MPG vs EPA rating.