we all have the same problem, has anyone got it diagnosed yet. To be specific, What is it?
I ended up taking it to a Mercedes dealership to get diagnosed. They took a look but couldn't find out the noise concretely on the test drive. They let me ride with one of the technicians to point out the noise. I live about 2 hours from the nearest dealership and by the time I got there, the noise was very hard to hear. The tech ended up saying it could be my tires in the cold and didn't charge me.
Noise does still exist unless I take it on longer car trips and then it's fine for awhile. Thinking I will know concretely one day if that isn't true or come warmer weather season and it disappears. I still have my suspicions on it being an axel of some sort, but what do I know.
Not sure if that is your case, but just wanted to shed some light on what I've experienced and what the dealership told me.