I have a 2013 GLK350, 4matic with about 47k miles on it. I've noticed that the engine seems to "buzz" and vibrate more than my older c320. It's definitely an engine buzz, not driveline. I can feel it in the pedals and steering wheel. I would think motor mounts, but at idle it's perfectly smooth. I know the old w163 ML's vibrated more because they used solid motor mounts. There's no clunking, or anything like that. Is this normal for a GLK? Seems odd that a 45k mile GLK engine would feel less refined than a 120k mile w203 engine. Any thoughts?