If you put the same generation tires on them, the McLarens will be faster than the 911 Turbos. Half the tests were done on Corsas from like 5 years ago. Remember, 650S is actually just a 12C from 2011 with a few more horsepower.

According to fastest laps, the 600hp 2011 12C did 7:28 on what were then Corsas. In the hands of a pro with newer tires, you could expect much better, not to mention that car was the original 12C platform before all upgrade they gave it.

The McLarens will put down all the exact same times with the top down too. How does the 911 Turbo perform when you make it a cabrio? 911 Turbos are excellent cars, but they're also 3-4 years newer.