I have a 1991 Mercedes 190e 2.3, and have noticed a rattle lately. It sounds like its coming from underneath the car and on the passenger side. It only happens when I'm accelerating. I can hear it when my windows are down and I'm driving next to a wall or car, somewhere where the sound can bounce off. Any ideas of what it might be? I'm thinking it could be something with the exhaust system, but thats just a guess.