If you are feeling vibrations in the cabin this can be down to a couple of issues.

1. If your car has more then 100,000 miles on it the engine mounts could be worn out as many Mercedes have oil filed engine mounts which can start to run dry after that.
2.  If you get this problem when your car is stationary this could be because of a bad coil which is making it miss fire.
3. If you are only getting this problem when you are driving then it could be the following things
   1. Wheel alignment
   2. Wheel balancing
   3. Bad CV joint
   4. Worn Bushings

There can be other reasons for this to happen but these are the most common, if you are having trouble working out what the problem is feel free to give us a call.