There is definately a difference in the driver's skills. The winning driver (RX-7) is Gan-San, he is older but is a VERY VERY agressive driver. He would rather run you over than let you win. He was the driver that ran the NSX around "The Ring" (Nurumberg or however you spell it) in under 8 minutes, 7M 56S to be exact. Majority of the time around The Ring track he had the NSX past the redline, the shift light blinked on many occassions. A great video to watch if you have not seen it. Someone posted it on Prime before.
Driver skill definately plays a big part of these races especially when the cars are "relatively" close in HP and handling