Not to dredge up the old stories about how the oil companies bought up the patents for super efficient carburetors. But I will relay stories that I have heard but not followed up on. True

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In WWII the allied tanks were able to out flank the Germans by not stopping to refuel their tanks and the Germans ended up running out fuel long before the allied machines did. As the story goes it was because of a secret carburetor used. Believe it or not but remember they also had synthetic gasoline that we havn't heard much about either. An old timer I used to work with told me of an experiment he and some budies did on their old 78 chevy van and the gist of what they had done was to vaporize gasoline and to mix it with the air in the intake and repotedly they acheived over 60 mpg. I don't believe the old timer would ever lie to me so I often wonder of the feasibility, but lack of time $$ and safty concearns have kept me from tinkering myself.