I am absolutely convinced that the 'fenders' was part of the American Retro influenece infiltrating the Mercedes design studio when it was in bed with Chrysler. The Fender trend started with the PT Cruiser -- and the US market [particularly] loves Retro styling.

The dashboard of the S class is vaguely Retro too. Obviously these Retro details are very watered down, they are subtle, but they are still there.

Mercedes design has been incorporating subtle Retro elements into their model line. They could be seen as "classic Mercedes styling elements" -- but lets be honest, it is all about using nostalgic styling to create a sense of history around the Mercedes brand. A great deal of it comes back to a marketing strategy.