Be very careful about what you use on the seats. It seems that BMW, in it's effort to go green, used water soluble dyes that can bleed out and make a stain worse. See this thread
http://www.bimmerfest.com/forums/showthread.php?t=1007129
I have used ‘wet wipes’ and standard upholstery cleaner with success and no problems. That said I do find that the seats mark very easily and am disappointed with them. Would never have cloth seats again!