The new BMW M cars are not exactly light. The F10 M5 is heavy and it takes a good amount of turbo torque to get it moving. But that generates heat, a lot of it. Several wide open throttle pulls will result in what you see below which is horsepower going from 498.2 at the wheels to 443.2 for a loss of 50 wheel horsepower after seven WOT (wide open throttle) pulls.
On a hot day not only will one lose a lot of power after a few blasts but this is not a motor designed with the racetrack in mind. Yes, all motors suffer from heat soak, but the classic naturally aspirated motors do have an advantage in power retention and avoiding limp mode to the heat generated overwhelming the cooling system as they do not put out as much heat and do not requite as much cooling.
The odd thing about this is that the motors are supposed to be Motorsport derived. This is BMW M after all, isn't it? Well it's supposed to be but what this graph shows you is that the new M cars are more suited to quick wide open throttle blasts than sustained runs. That used to be AMG's game. Now it's BMW M's.
All dyno runs WHP vs WTQ
Highest/Average/Lowest dyno runs WHP vs AFR
Highest/Average/Lowest dyno runs WHP vs IAT (measured after MAF)