Motor mounts commonly fail, causing engine vibrations to be transferred to the body. Failed motor mounts should be replaced in order to prevent damage to the transmission mount.Google+
Car Problem Reports
Mercedes-Benz 300SEL Motor Mounts Fail and Cause Vibration in Body
Mercedes-Benz 300SEL Problem
Visitor, 1991 Mercedes-Benz 300SEL, 157,000 mi
My motor mounts are destroyed and my car vibrates at idle. As soon as I put my foot on the gas though it stops and its as smooth as cream and a lot of power.