When I bought my first Mercedes (a used '88 260e) the first thing I noticed was the high rpm's on the highway. I was used to my Volvo that ran about 2500 rpm at 65. Now, after driving the car for 4 years, I appreciate the passing power afforded by the high revs and actually feel uncomfortable driving a low revving car.

Noise is not a problem as a previous post mentioned. The engines run very smooth at high speeds and the cars are well soundproofed. The tach is normally the only indicator of what the engine speed it.