Purchased my 2000 S430 as a pre-owned. It had 56,000 miles on it, and the rack & pinion had to be replaced. It also has a high rear-end gear noise between 50 and 60MPH. The driver side sun visor no longer stays in place, and I had to tape it to the roof. There is rear vibration between 60 and 80MPH, though it has new Continental tires balanced by the Mercedes dealer. An A/C sensor failed at 57,000 miles, which caused the unit to freeze up. The CD player has started locking up, though it has been cleaned.
It is a very pretty designed car with lots of neat electronic ideas. The voice command is a lot of fun, though not very practical.
The basic drive train motor, transmission and differential should never be an issue with a Mercedes. Mercedes should own up to their mistakes and recall all their poor quality automobiles.