I once went on a 'drive day' at Bruntingthorpe, Leicestershire. It was run by ex F1 driver Jonathon Palmer. There was a very tight chicane on the circuit and I patted myself on the back because I managed to get through at 60mph. I was driving a Ford Escort with a 2.9 litre Cosworth engine with turbo. I then did a couple of laps with Johnathon Palmer driving. He drove the whole time with one hand, with his left arm over the back of the seat so that he was half turned towards me while he talked. We approached the chicane and he said 'we can take this at 100mph' and he did. I suppose knowing what a car is capable of is half the battle but I still wouldn't have fancied doing it at that speed.
Also drove a Formula Ford single seater that day which was interesting. My favourite was the Caterham Special which was a twin seater. We drove it round a special track with roundabouts and chicanes, tight bends etc., It was so responsive that you could take the roundabouts by hitting the brake then the accelerator and broadsiding all the way around. This was back in the 1990's, still got some photo's of the day.