There was this stuff I used to use to clean my carpets and headliner in my Jeep (also had grey interior) and it worked awsome. It removed grease, mud, you name it without any dicoloration and it didn't affect the headliner. I forgot what it was called since I used it like 3 years ago. It comes in a Silver and Blue aerosol can and I think it starts with a Z. I'll try to find the name of it, I might still have the can somewhere. Steve [Redundant quote trimmed by moderator]