Shwep, I think your sourse of informatin is in error, the charts I have seen show LNG around 58000 BTU, Propane around 57000 BTU and Butane at 55000 BTU, way less than any type of alcholol. Edit, I'm not sure of how much propane in liquid form turns into as a gas but as I already said that old Dodge truck averaged right at 7.5 MPG on the cheap regualr gasoline and 6.0 MPG on propane. Propane was way cheaper per gallon than gasoline then so it was a little cheaper to run for the same distance as gasoline so it was a advantage except for killing the exhaust valves.