That looks almost identical to the front end of the X6 that has been posted in the other forum to me. Maybe they are just testing cooling capability which helps explain why it's being tested inte US. I don't think this in an M/// car as it's too early in the product cycle for it to appear even for early testing. Also I think we'd have seen pictures of it pounding the Nurburgring first as all protoypes for the M/// are developed in Germany.

In an article about the new M3 I read recently a journalist visited the M/// factory, in it he did mention there was an X5 under sheets in there so who knows.