It looks to me like there is a small wheel that is being turned by friction on the car wheel that drives the flat belt to the buzz saw as shown in David Babcock's photo in Flywheel Forum, in the December/January 2016 issue.
My grandfather used his cut-down Pontiac sedan to cut stove wood for grandma. He mounted a flat pulley to the hub instead of a wheel, and with the belt twisted into a figure eight it gave the proper rotation for the saw blade. In the posted photo, you can see that the belt is running in a standard loop. A buzz saw always rotates like one on a table saw, spinning toward the operator.
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