Same. Had the engine mounts replaced in a 14 month old GLS250d. Seems to have fixed the vibration. Mine was that bad that the eco stop function wouldn't operate.
Hi I have the same issue did you ever get it fixedhi, i have recently bought a 2016 glc 250d and it has a slight shudder on the down switch from second to first, just before 1st gear engages ... took to main dealer and after two days said it was the engine mounts ... the warranty mechanic replaced the left-hand side mount and said these often went but said the right-hand side was in good condition and did not need replacing ... shudder is still there ... claims it is not the engine mounts ... any thoughts?