Bare bones racer. I remember reading some articles about them off and on in the 60s. I actually saw an original one needing restoration, for sale at Petti Jean Antique Car Show here in Arkansas a few years ago.
Bill Thomas' Cheetah was another of many cars that filled the modified sports car classes of the late '50s and early '60s. Another of a similar design was the Devin. Devin were both pre-assembled cars and kit cars, and designed to run anything from Triumph and MG power and drivetrains to Chevy small blocks.
There were many cars that had this same basic shape in the '50s and the Cheetah basically took it with a coupe body and moved things further back to get even better front to rear weight ratios. If you look closely, the driver is nearly between the rear wheels. It was probably too much, as most accounts I have heard of said they were wicked to drive.
I believe Tom is accurate on the weight, as they were lighter than the Grand Sports. If you notice that second picture at the top of this thread, you see a Grand Sport behind the guy standing on the right.