Not going to be the ///M5- this a test vehicle for one of several future engine variants. The giveaway is the rear exhaust not being quad tipped. During testing they actually make sure that the tips blacken equally (or not), unlike the Dinan exhaust where they made the tips black since two are just for looks. Also looks too long to be a 5er but that is another story...
I wish the images were able to be made larger so we could read some of the notes....
nice find!