How to Improve Fuel Economy
Written by Muneeb Rana · Last updated 21 October 2026
Quick answer: To improve fuel economy, drive smoothly, keep speeds moderate, keep tires inflated, remove roof racks and extra weight, avoid long idling, and use the recommended oil. FuelEconomy.gov says aggressive driving can lower highway mileage by 15-30% and city mileage by 10-40%, while proper tire pressure improves mileage by about 0.6% on average.
TL;DR
- Smooth driving saves the most.
- Each 5 mph over 50 costs about $0.30 a gallon more.
- Tires, weight and roof racks add up.
Here's how to improve fuel economy with changes that actually work, ranked roughly by impact, with figures from the US Department of Energy's FuelEconomy.gov.
Driving habits (biggest impact)
- Drive smoothly: gentle acceleration and braking. Aggressive driving can lower gas mileage by roughly 15-30% at highway speeds and 10-40% in stop-and-go traffic.
- Slow down: fuel economy usually drops quickly above 50 mph; each 5 mph over 50 is like paying about $0.30 more per gallon.
- Use cruise control on highways where safe.
- Avoid idling: idling can use a quarter to a half gallon of fuel per hour, depending on engine size and AC use.
- Plan trips: combine errands; a warm engine is more efficient.
Car and load
- Remove roof racks and boxes when not in use: a roof box can reduce economy by about 2-8% in city driving, 6-17% on highways and 10-25% at interstate speeds.
- Lose excess weight: an extra 100 lb can cut MPG by about 1%.
- Keep tires inflated to the placard pressure (tire pressure guide).
- Use the recommended oil grade: can improve mileage 1-2%.
Maintenance
- Fix problems promptly: a faulty oxygen sensor or misfire can hurt economy; don't ignore the check engine light.
- Stay on schedule with the maintenance schedule tool.
- Don't expect miracles from air filters: FuelEconomy.gov says a new air filter doesn't improve MPG on modern fuel-injected cars.
Measure the difference
Track every fill-up and work out your real MPG (how to calculate MPG) before and after changes. CarO's fuel log keeps fill-ups and costs per car, and the fuel cost calculator shows the savings in money.
Download CarO free on the App Store or Google Play. Free with ads; optional in-app purchases.
Sources
- FuelEconomy.gov: Driving More Efficiently: www.fueleconomy.gov (accessed 21 October 2026)
- FuelEconomy.gov: Keeping Your Vehicle in Shape: www.fueleconomy.gov (accessed 21 October 2026)
- FuelEconomy.gov: Find and Compare Cars: www.fueleconomy.gov (accessed 21 October 2026)
Disclaimer: CarO and this website give general car-care information, not professional advice. Maintenance intervals and specifications vary by vehicle, so always follow your owner's manual and a qualified mechanic. Mileage and cost figures are estimates; check local tax rules before using any log for deductions.
FAQ
What is the best way to improve fuel economy?
Smooth driving and moderate speeds give the biggest gains, followed by correct tire pressure and removing roof racks and extra weight.
Does driving slower save gas?
Yes, above about 50 mph fuel economy usually falls quickly, so moderate highway speeds save fuel.
Does AC use more fuel than open windows?
AC adds load, especially in town. At highway speeds, open windows add drag. The difference is usually modest either way.
Do fuel-saving gadgets work?
Most don't deliver meaningful savings. EPA has tested many and found little or no benefit.
Does tire pressure affect fuel economy?
Yes. FuelEconomy.gov says proper inflation improves mileage by about 0.6% on average and up to 3%.
Related guides
Track this in CarO
CarO is a free car maintenance tracker app for iPhone and Android that keeps a full service history, reminds you about oil changes and inspections by mileage or date, and logs fuel fill-ups with MPG, odometer readings and car expenses for every vehicle you own. Logs are stored in the cloud and can be exported as CSV.
