Maybe its just a 4 series with the M Sport Package?
I can't see the M4 coupe beign debuted before the M3 Sedan, especially when the regular 4 series hasn't even been shown.
4 series coupe with M Sport package and quad exhausts could be possible! would make the M Sport package more appealing!
"Edit" just noticed the F_2 tape, could just be a tease, the 4 series coupe is the F31, right? M Sport would still be the same number...