The BMW M5/M6 are beasts from a roll and accelerate on par or better than supercars in the 400-600 hp range solely because of the gear box. It greatly makes up for the lack of about 75-100 ft/lbs of torque that its competitors have with larger 5.0+ ltr engines or super/turbo charged engines.
It is in its peak power band just that much longer due to that extra gear and the advantage of a computer making shifts faster than a human can.