Any idea what might cause a loud rattle sound at <> 60 KPH and only when the drivers window is down It's coming from somewhere in the back of this new Metris. I've tightened anything that could possibly rattle but it still goes on

What is your question?

Someone mentioned that it might be the mechanism for the sliding door. This rattle doesn't happen going over bumps or any other time except when driving along at +/- 60 km/hr with the drivers window down. Pretty load and sounds like something loose slapping around somewhere. Mercedes tells me there are no bulletins and they have no idea where the rattle is coming from . Van only has 10K Km on it. Frustrating!!!

What makes this problem better or worse?

N/A

How long has your 2017 Mercedes-Benz Metris had this problem?

Since day one