CLK 430 steering linkage and high speed cabin noise

1)When you swing the steering wheel left or right there is a loud knock as though something is lose in the steering linkage. My dealer says that all CLK's are like that. Can that be true?<br><br>
2)When cruising at 80 mph plus, a low level droning noise kicks in but there is no significant vibration. I have had all the wheels re balanced but no difference.

the drowning noise ...... does it happen when the sunroof is open but no windows ??? is so that's what it is .... mine does the same ..