Jim Hall, along with Mark Donahue were the two guys from the US that were mechanical genius who took their engineering education and applied it to auto racing like nobody had before. Funny how he got the hooked first in the no rules road racing. Lucky the 100 didn't catch on fire! The vacuum cars did run is several races. As I remember they used snowmobile (2 cycle) engines to drive the fans. They would pick up all kinds of stuff off the race track and kick it up into the air. You could actually see the car suck down to the road when they cranked up. Just part of his genius and guts. Jim built everything from the Trans Am Camaro to Indy cars. Few have ever spanned that many racing series.