Nobody mentioned it... - You do realise, your car has 4-wheel-drive, yes?
Our 300E 4matic has plenty of miles, never with any problems, except needed tranny rebuild at 175,000 or so.
Your problem sounds nothing like the usual problems leading up to a big $$$ tranny fix though, so don't worry.
Have you driven many automatics before? I always used to think they disengaged when you let off the throttle pedal too.. right until I first drove one about age 14. If they did don't you think it would be pretty horrible? No engine braking either!
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black