I took one of those 3 day racing courses (lots of fun, highly recommended!). We drove Formula Fords, with classroom lectures interspersed with track practice.
Early on, we were limited to 50 mph, and were sent out to practice racing lines around Watkins Glen. We thought we were hot stuff wheeling hard around the turns.
Then the instructor told us to get in the van and he'd drive us around giving us pointers. He drove with his left hand on the wheel, and his body turned around facing backwards at us while he lectured us. He was sliding the van around the turns at 70 mph, and I doubt his heart rate exceeded 70 BPM.
It was a very humbling experience.