Turned them facing each other (elite, hotseat)
M2 spotted first every time
seconds it take M2 to spot BMP
11, 4, 10, 2, 5, 23, 4
BMP had ?spot 3 times after it was fired before getting destroyed.
EDIT
started game again to get 10 results
3 runs
M2 spot first once (6s)
BMP spots 2 times first 3 & 14 , M2 release smoke and proceeds to destroy BMP. Both times BMP gets even another spot when M2 drives out of smoke cloud.
In all of these 10 times BMP never fired a shot.