I think everyone is taking the race a bit seriously, clearly it's a demonstration done for TV/camera crews.
It's not an indication of their various speeds around the track an M5 can't keep up with a Gallardo or the Z tune.
For relevant times wait till the very end of the clip and the time attack ones are listed in blue.
Lambo: 1:37.537
GTR Z tune 1:37.554
M3 CSL 1:39.938
911 S 1:40.298
M5 1:41.885