Check the upper shroud on the shock absorber. May be bent or broken loose. I have seen this two times, however, neither was an MBZ. Also, look for any missing or broken parts in the exhaust system.

__________________
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.