So the F10 M5 makes more power but has another 1000 pounds to carry around. The F10 M5 has also lost to a stock P31 C63 AMG in a roll on race which weighs 700-800 pounds more than the Z06 and makes roughly 35 less horsepower at the wheels than the Z06. So, BimmerBoost is left scratching its head on this one.
Even magazines routinely get ~125 miles per hour of the C6 Z06 in the 1/4 mile whereas the the M5 is in the ~120 range trap speed range meaning the C6 Z06 is favored from a roll, favored from a stop due to its weight, favored basically everywhere. The fastest 1/4 mile trap speed recorded for a stock F10 M5 is Car and Driver with a 122 mile per hour trap but Car and Driver got 126 for the Z06 so... these races make no sense.
The Z06 simply has a much better power to weight ratio so why the result is what it is I have no clue. The M5 clearly pulls up top in multiple runs whether it gets the jump or not. Let's just hope F10 M5 owners don't start thinking their car is now a Z06 beater as this will no doubt inflate some egos. From the looks of things though the M6 may have a shot to at least make it a race against the C6 Z06 with how it has shown against the Nissan GTR recently.
Video is below, you make sense of it.