Another unorthodox method of cleaning is to use a very water diluted "Soft-Scrub" with a wet paper towel or wet soft cloth.
I've used this on many different types of materials: plastic, chrome, silver, appliance finish, mini-blinds, tile-basically anything that's stained and other products don't work.
Try it in an inconspicuous place first and don't rub very hard, it will leave remove paint and for other materials and especially on plastic it may leave an opaque area.
2004 E60 530is, Delivered 12/12/03, TiSilver/LGrey, PP, SP,PS, PDC, ACC, FRS, Step, Xenons, clear bra, body colored rear inserts. (Retired, 1983 henna red 320is)
2004 Corvette Z06 Commemorative Edition