1) Save Up To 40% - Fixing a car that is noticeably out of tune or has failed an emissions test can impove its gas mileage by an average of 4.1 percent, though results vary based on the kind of repair and how well it is done. If your car has a faulty oxygen sensor, your gas mileage may improve as much as 40 percent.
2) Save Up To 10% - Replacing a clogged air filter -can improve your car's gas mileage by as much as 10 percent. Your car's air filter keeps impurities from damaging the inside of your engine. Not only will replacing a dirty air filter save gas, it will protect your engine.
4) Save Up To 3% - Check Tire Pressure - You 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 0.4 percent for every 1 psi drop in pressure of all four tires. Tires usually drop 1 psi per Month Properly inflated tires are safer and last longer. Each tire should be periodically spun, balanced and checked for out-of-round. Check manufacturer's specifications for maximum tire pressures.
4) Save Up To 1% - You 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
