I'm new to the forum but I thought it worth mentioning that my C200 sport W205 developed a grinding noise when turning the steering wheel. I took it to Mercedes who told me that it is "very unusual" but took it in to look at. They returned it to me with a new steering column, saying that it is very common for this to happen. Mine is an early production of the new C Class and apparently there was a manufacturer's recall for this model to clip the cover of the steering column into place as they were not properly fitted at the factory. The new steering column has been redesigned where it clips in so I am assuming that the original clips can come unattached and needed improvement.