One of the issues that must be addressed with these HP comparisons is that most of them obtain their numbers with forced induction via superchargers or Turbos.
For a car designed for the track, these compressors are not a viable option as they quickly heat soak and the performance will vary greatly lap to lap. Porshe has done perhaps the best at this, but still for dedicated track models, naturally aspirated engines are usually fitted.
Coming off a corner with forced induction is a real challenge for drivers, as the boost and power is not controlled so much by the throttle as by engine RPM's. Just when you need to back out of the throttle a bit, the power continues to rise and the driver has lost control over torque when the engine takes over that modulation.
For a big heavy Autobahn runner, this gives a great feeling of power, but for a track performance vehicle it cannot be tolerated.
For driving on the edge, such as the NRing, exquisite throttle control is manditory for fast times.
