I wanted to share since I never saw a topic on the subject. In the past I was just using any old carpet cleaner on the inside part of it when it got dirty. Well I didn't really care too much since I was just covering up a damaged bumper anyway. Well now that I got a bumper repainted I was more concerned about it. I was thinking that the chemical from the cleaner might do something to the paint. So I layed it out and sprayed Simple Green all over it. This was good because it cut the grease that was on it. Then I sprayed it down and VOILA looks like new.