Guys I found out what this noise was. After 3 test drives at the dealer, one of the employees stuck his head out the window at low speed to see if he could hear it - and he did, but it was coming from the back.
So we get back and throw it on a lift, and find out there is this huge BOLT in my right rear tire. Like 2 inches long, threaded, flat tip bolt. Who knows how THAT got in there.
So I found the cause of the noise, which is good. Now I have to decide whether to get another RE92 or 4 new falken 512s/conti extremes/toyo proxes4 take your pick. On to the tire forum...