A Car Wash Improves Your Fuel Economy A clean vehicle results in less wind resistance. Reduced wind resistance results in improved fuel economy. While some have argued in the past that driving a dirty car actually boosts aerodynamics, MythBusters proved them wrong on an episode of the popular TV show. When cars are dirty, there is no rhyme or reason to the placement of the dirt. This creates more drag as the air particles grab onto the grime. MythBusters calculated that a filthy car can reduce fuel economy by 10 percent.

"Protects Your Vehicle’s Paint Those who wash their vehicles by hand create small scratches in the paint. These are produced because of the tiny particles of dirt, silt and sand that are trapped within the sponge and brush. Alternatively, brushless car washes utilize a harmless high pressure water spray.