Every time one of these threads show up, I think of the Smokey Yunick gas-vapor engine. It's been over 20 years so my memory is a little cloudy, but I think the basic idea was heating the inlet charge to a point where the gasoline changed from a liquid into a gaseous vapor, which was then "mixed" with the incoming air on a turbocharger. Smokey was able to double the horsepower and MPG on a 2.5 Fiero.