The engine works best when each of its individual parts works correctly. Having your vehicle inspected and maintained at regular intervals helps maximize engine performance and efficiency.
Fixing a car that is noticeably out of tune or has failed an emissions test can improve its gas mileage by an average of 4 percent, though results vary based on the kind of repair and how well it is done.*
Fixing a serious maintenance problem, such as a faulty oxygen sensor, can improve your mileage by as much as 40 percent.*