The poser are running rampant these days. So much that it has the attention of good old Donald. lol.
As an M3 owner myself, I'm not sure if I would confront a poser in the giving situation. However, If I did, I would probably ask a question unique to the M variant such as what's the top speed on the tach, and if he or she said anything less than 200 mph and it's a late model BMW, I would immediately walk away
There are those that fail to or don't want to understand that M trim does not equal a true M car.