Changing from liquid to gas is item #2. If you use a theoretical carburetor or preheat to change it before the combustion chamber as you suggest, you do not get to capture that change to do the work of moving the piston. It needs to enter the combustion chamber as a liquid. The smaller the droplets are, the more rapid the reaction.
I found a story of a man on one of the mpg's site whose fuel pump was malfunctioning and overheating, causing the fuel to heat up. He was getting about 45 mpg's when he was normally getting about 23.
I've read a lot of stories about Bigfoot, UFO's and Elvis working at a convenience store. Repeating a fabrication does not make it true, and it does not change the laws of chemistry and physics.
This is a typical automobile.
The only part you suggest is being changed is 62.4%. That is a huge loss, I agree. But your examples are doing nothing to reduce friction or capture the waste heat given off the engine, radiator and exhaust. It is not magic, but a chemical equation and basic physics.
but the oil companies have made it difficult by reformulating the gas to a very high vapor temperature
Raising vapor pressure means more vapor is produced. Vapor pressure is a measure of the amount of gas that would natural occur as a liquid is put into a closed container. If a what you claim is true, it would produce more, not less, vapor.
Vapor pressures are regulated by the EPA. They force the fuel to be reduced vapor pressure.