This guy here on the Youtube has a couple of videos of the driving done with all the fancy data recording stuff. The difference in speeds between the lead/follow and the instructor hot lap are noteworthy.
View: https://www.youtube.com/watch?v=voHKg2aJuJA&list=PLjHzbb1uFu4-kPFSy0wgzXBeOE16O_J1j