On paper, the McLaren is lighter (rear wheel drive instead of all wheel drive like the 991 Turbo S) and more powerful at 616 horsepower to the 991 Turbo S 560 horsepower.
So Chris Harris got his hand on both and pitted them against each other in the real world. So what happened?
In the drag race the McLaren gets a slight jump but the all wheel drive of the 991 Turbo S eliminates the advantage quickly. As speeds rise, the McLaren MP4-12C simply pulls away. This is exactly what should happen and is in stark contrast to the junk AutoCar gave us of a short sprint between the two on a tight road that showed the 991 Turbo S coming out on top.
Now, the problem is as you often have with Chris Harris videos is the lack of hard data. He gets both cars on the road course but provides only his impressions and no laptimes. It is obvious to see what happened in the drag race for example but without data we can only speculate regarding how even the cars are up to the speeds he quotes. He really needs to start providing proper data rather than just his opinions.
That said, the MP4-12C is the faster car here and likely quicker around the track. We will have to wait for a proper track comparison to know for sure.