On the VW forums, and more generally on any forum about mechanics, there's a topic which comes around on a regular basis : the Pantone ngine, a.k.a "water engine" or water injection engine.
At the end of the day, it's more or less like the Loch Ness monster : everybody has heard of it, or knows the neighbor - of - a - cousin - of - a - mate - of - a - friend who made it, and it worked. But in fact, very few have actually seen one of those.
Anyway : here is a gem dating from 1949 :
This is an add, scanned out from a HotRod Magazine (June 1949 issue), promoting the virtues of water injection in the carburetor.
It doesn't bring any actual answer, but proves that the idea is pretty old!