It's a Concept CS, or a CS-based variant (like a 2 door as people have suggested). It could even be the new 7 series for all we know.
I don't know why it woud be a new M6, as some have said. And it sure as hell ain't no F30 3 series concept. That concept rendering is complete BS.
E92 335i: Space Grey|Coral Red|Aluminum Trim
Hold out for the BRZ STI or... Rocket Bunny FRS. Update: Scratch that. I've got a 2015 5.0/6MT with my name on it.