I just purchased a 2001 300M with 57000 miles on it. I was driving it home thinking about how great it was running, shifting etc when the tranny disengaged. I could not do anything to get it back except that if I shut the car off and then turned it on again, I could crawl forward in drive as long as I did not go over about 1000 rpm. I lost reverse and all other gears. Engine codes P1684 and P0700. I have a hard time believing that the tranny went out at this mileage and wondered if anyone had had a similar problem. I should mention that this was the first drive of the car at a considerably higher altitude in case that has anything to do with it.