I believe it was mostly promotional for Nissan. Had the Skyline not been there, the S2000 would have certainly passed the Z. The M3 also would have made a much better showing. It got off to a bad start because the Skyline blocked the S2000 on the first lap, which in turn blocked the M3. The M3 driver just hung back for the first lap or two.
I love near the end when the M3 powerslides around that one corner. Some great drivers there. That old man is pretty awesome, reminds me of my late Grandfather.