Check Tire Pressure: Keep tires properly inflated and improve gas mileage by up to 3.3 percent.
Use the Right Motor Oil: Improve gas mileage by 1 to 2 percent by using the grade of motor oil recommended by the manufacturer.
Replace Clogged Air Filters: Replacing clogged air filters on older vehicles can improve fuel economy and will improve performance and acceleration on all vehicles.
Check Engine Performance: Keep your engine running efficiently and improve gas mileage by an average of 4 percent.
Fix It: Addressing a serious maintenance problem, like a faulty oxygen sensor, can improve mileage by as much as 40 percent.