I cant hear the audio but it Looks like the M4 has CCB on it. Still think it would be faster than the RS5 but not by the same margin at all. Those brakes, if on this car, are insane for this comparison. At least have the same spec in the RS5.
Love how these car mags seem hell bent on mismatched comparison tests. Of course a weaker braking car will lose. Especially the heavy RS5.