Thanks. Does the stiching look stock to you? A re-dye might be possible (how many coats of Leatherique would that take??!!) but I haven't seen the car in person yet, so I'm not sure if it's a re-cover job or not, and I don't know enough about BMW's upholstery patterns to be sure.
It's an early M635 that I'm in the process of negotiating a buy. Now I know why the seats didn't seem to match the colour of the dash and door trim (definitely a mid-brown, therefore Nutria). If the seats are re-covered, I may negotiate a bit off the price. If they're original, but restoreable, I'll probably pay closer to the asking.
Thanks again. And Batmobile, if you could post those pictures I'd appreciate it. I found the M5 on the register, but more pics is always better!