I suspect two things in this data:
Originally Posted by dunderhi
Using a calculator at Wallace Racing I get the following:
1) M5, 114.6mph and 4137lbs yields 512hp. (data from MotorTrend)
2) 550, 106.9mph and 4354lbs yields 437hp. (data from MotorTrend)
3) RajG, 110.6mph and 4550lbs yields 506hp. (from RajG's data above)
4) Me, 112.9mph and 4760lbs yields 563hp. (my best trap speed & measured weight)
I suspect BMW's stock numbers are in general underestimated, but I believe BMW quotes minimum performance numbers since manufacturing variances will produce engines with different power levels; every engine does not leave the factory with the exact same horsepower.
1) weights for published cars.
2) AWD launch advantage.
The AWD launch advantage can't be overlooked.
I think those two things are skewing the calculations a bit.
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Hell is where the police are German, the cooks are English, the cars are French, the lovers are Swiss, and it is all organised by the Italians