The BMW M550i doesn't make 530 ps, it makes more like 585 for Euro-spec cars and 635 for US- and AU-spec cars. Remember, the German and British automakers rate their turbocharged motors using wheel horsepower.
As opposed to most NA and SC motors, in which case they rely on SAE bhp and DIN/EEC crank metric hp figures.
But even many of the old big-block Chrysler, Ford and GM motors were rated at whp, posed as hp. 255 hp out of the 454SS pickup's 7.4L? Definitely screams whp.
In reality, the M550i has, on average, 321ps/tonne—beating the Gallardo, but trailing the F430 and especially the FGT.