The 4-cylinder engines may or may not be noisey, but I'm sure most the mechanical noise you hear is the supercharger.
Every automotive magazine the has tested any MB model with the supercharger has commented on how noisey it is.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".