Your car air filter is something that should be replaced about every 15,000 miles to help your car run as efficiently as possible. A dirty air filter can affect your car's fuel economy and overall performance. But to help keep your car's air filter in tiptop shape between replacements, consider giving it a fast cleaning. Simply removing the air filter and using a nozzle attachment on your vacuum can remove dirt, debris and other contaminants. And while soap and water will definitely get it cleaner, you risk putting a wet filter back into the car, which can cause more harm than good.