German cars tend to be different than their American counterparts. Back when I was into Chrysler, Ford and Chevrolet, it was easy to throw an aftermarket part on the car and save a few $$$$.

One thing I've learned rather rapidly in the world of German automobiles is this:

They don't like you screwing up by installing non-standard parts. Mercedes Benz has a master design plan which involves the utilization of part number specific OEM parts. Unfortunately, they can't stop you or anyone from approaching the car like a it was a Chevrolet by mixing and matching parts and components.

When it comes time to either sell or trade in a Mercedes, a thorough mechanical exam will reveal the owner's mix and match parts philosophy which may result in a lower resale or trade in value.