There has to be a million stories about this thing online, and I've read many of them, but NOT ONCE has anyone commented on it's crankcase fume burning system... and the effect that would have on fuel economy... and of course, the obvious fraud that's been perpetrated for 36 years now.
It's set up with a side draft carb that breathes
ALL THE INTAKE AIR through the crankcase, after being preheated by the "radiator". Spike the sump oil with gas (or even run 2-stroke mix in there), stir and heat, and Voila!- an engine that runs even with a completely empty "gas tank".
There is no trans and the associated typical gear losses; just a clutch with outboard support bearings and a chain.