Hey Guys,
First post here, just started browsing earlier today. Excellent forum so far
I too experienced the vibrations in my right rear door area, I even made a point to record a video of it, and forward it to my sales associate, just to confirm it existed before I got the windows tinted. Anyway, I was able to troubleshoot my issue for the most part (perhaps it's not the same issue for you guys). I determined that the bottom of the rear door panel (plastic) is not actually secured at the bottom and there is some wiggle room between the panel and metal of the door. There's 3 or 4 areas where there are tabs on the panel that stick out and rest against the door (you can slide a finger under the bottom edge and feel these spots). I was able to place a bit of dampening material, roughly postage-stamp sized squares, behind the plastic tabs, between the door panel and the door. 95% of the rattle was gone, it's only the rarest resonant frequency that I get a brief rattle on occasion, and I believe it's because I didn't pad the front most tab (in line with the passengers seatbelt mounting position). When I took delivery it happened every time I rolled out, at basically 2100rpm with the exhaust valves open. I hope this works/ helps for you guys. I was reluctant to have them start ripping the car apart, for the obvious reasons, so I was really happy to find an at home solution without having to remove door panels on a car with 100 miles.