Your car’s air filter works to remove dirt, debris, and particles that might otherwise damage your engine. Replacing a clogged air filter on an older car with a carbureted engine may improve fuel economy 2 to 6 percent under normal replacement conditions, or up to 14 percent if the filter is so clogged that it significantly affects drivability.

E.H. Gill/Custom Medical Stock Photo/Newscom/File
Replacing a clogged air filter with a new one (such as the one pictured here in this 2010 file photo) can improve fuel economy up to 14 percent.