BMW could be testing a hardcore CS version of the hot M5 sedan, and we have the spy photos to prove it. The white prototype caught testing on the Nurburgring Nordschleife is believed to be it since we can spot several things it has over a regular M5.

It is probably based on the enhanced M5 Competition that’s already on sale but is believed to be even more extreme than that. We think this is the CS because its modifications resembled those BMW made for the M3 and M4 CS.

It could even offer a small power hike over the M5 Competition, on top of the other performance enhancing modifications.