1998 520se with steptronic - 171,000 miles.
Bought from new.
From day one the thing has occasionally given an almighty jolt and bang kind of like running over a brick.
It only happens once a week maybe (then 3 times in the same journey) whilst kicking down from 5th to 4th at speed on the motorway.
I moaned to BM dealership but they never really took me seriously since they said they couldnt drive at 80mph and "boot it" legally to see for themselves.
Oh Well - it's nearly ready for the big scrap yard in the sky anyway