Car Maintenance That Actually Saves Fuel (and One Myth)

What helps

• Tyre pressure: keeping tyres inflated to the proper pressure can improve gas mileage by 0.6% on average, up to 3% in some cases, and under-inflated tyres can lower it by about 0.2% for every 1 psi drop. Properly inflated tyres are also safer and last longer. Use the pressure on the door label or in the manual, never the sidewall maximum.
• The right oil grade: using the manufacturer's recommended grade of motor oil can improve gas mileage by 1% to 2%. For example, 10W-30 in an engine designed for 5W-30 can lower mileage by 1% to 2%. Look for oil marked Energy Conserving on the API performance symbol.
• Fix engine warnings: the check engine light may be something minor like a loose gas cap, or something more serious that reduces fuel economy, raises emissions or leads to costly repairs later. Have the vehicle inspected.

The air filter myth

fueleconomy.gov says replacing a clogged air filter on vehicles with fuel-injected, computer-controlled gasoline engines, such as those made from the early 1980s to now, or on diesels, does not improve fuel economy, but it can improve acceleration. On an older carbureted engine, replacement can improve both by a few percent.

What to do

• Check pressures monthly.
• Follow the owner's manual for oil grade.
• Do not ignore dashboard warning lights.
• Do not expect a new air filter alone to cut your fuel bill on a modern car.

These are US government figures. Your own results will vary with the car, roads and climate.

Fact-checked on 30 October 2026 against the sources listed below. Tax rules and prices change by gazette, so confirm with Sri Lanka Customs or the Ministry of Finance before you pay.