If I was to buy a used M5, I would look on the M5board.com. Check out the member, look over his history of posts and see what has been done to and with the car.
No where else and no other time in history could information like this be had.
"Ah, I love the smell of fresh cosmoline in the morning"
"Motion does Not equal progress"... Cos.
"It's NOT A.D.D., they just do not make anything for my car yet"