I have a 2002 Mercedes Benz E430. When idling, it sounds like a coffee can of marbles shaking under the car. It’s under the middle of the car, behind the engine and transmission. What could this be
The likely cause is your muffler system. It could be a simple heat shield that has broken a weld(s) and is rattling. You do not have to visit a dealer to correct this annoyance. Any independent garage can diagnose this one.