Hey all!
I have used this stuff before on an old GTI I had and it works great. Lasted at least 5yrs (until I sold my VW).
http://www.customfinishes.com/Vinyl-Carpet-Dye.htm Now that I have recently bought a 1997 318ti with the stock cloth interior, the black seats are faded a nice shade of blue. Since the seats are still in great shape (no tears or rips) I am just going to re-dye them black. I can't vouch for other brands, but this CFI stuff is very color fast and doesn't rub off. It didn't fade in my old GTI after 5yrs and it felt like the original fabric to the touch. (I dyed my GTI's seats because I couldn't stand the confetti pattern!)
To do it, I will just remove the front and rear seats, remove all the plastic trim and parts (and clean those up) from the seats, tape off anything that I don't want dye on, and spray.
2 coats sprayed 90deg to each other for even coverage will make them look like new! I would wait at least 24hrs before I considered putting the seats back in.
Good stuff. Works great. Since it's a dye I wouldn't try to change the color rather I would just match the OEM as close as possible. Works on the cargo cover too!
~Mike R~