It blows my mind that after five years, the discussion always ends up revolving around the fact that there is not a manual transmission, year in and year out. Seriously, were people realistically expecting one to magically appear for the 2014 model?
Anyway, I watched some of the videos about it, and Mizuno pointed out that the GT-R used in their 'Ring test was the same as the standard production cars without any special packages. I think it was a slight jab at cars like the Z06 and ZR1, as I think that the cars used by GM on the 'Ring were the ones with those race tires and other stuff that are optional and likely not on many of them actually sold.
But what none (or at least very few) of the reports are indicating is that the actual lap time was 7:19.1 because the test driver had to let off of the accelerator to pass an unexpected car also on the 'Ring at the same time, and Mizuno's estimate was that it added around 0.5 seconds, so they claim 7:18.6.