”A clean car gets better gas mileage–a proven fact.”

This statement can only be true at highway speeds. In the real sense, the car’s mpg may not be affected by a little dust on the cars body. Equally we can say that there is no measurable effect of a little dirt on the cars mpg. However, if your car has big clumps of dirt that considerably alters the flow of air along its surface, then it reduces your gas mileage. This can be supported by the fact that large clumps of dirt on the body of the car disrupt the air around it creating a stir behind it hence reducing drag.

The statement is true if we look at a clean car in the sense of a well maintained, repaired and upgraded car especially on the vehicle systems like intake, exhaust, suspension brake and electrical system. For instance replacing a dirty gas filter will enable your car to breathe easily hence using less gas thus increasing gas millage by more than 10%.