The outing was made possible by Miller Motorcars, with most of the cars being customer cars (they note in the description that this was why they couldn't "get on them hard"). The cars showing up were the Ferrari LaFerrari, McLaren P1, Pagani Huayra and Porsche 918 Spyder. Between them there's thousands of horsepower and the finest engineering in the automotive world.
Check out the video below to see all of the cars rip up the track together.