100 octane = good
ethylene = good
ethylene absorbs water = possibly good
But how much? Is it constant?
different energy density, mass, etc .. means you need to tune specifically for it.
But if the fuel you buy from one week to another is not constant in all relevant qualities,
tune has to be very conservative so possibly negating any advantage. ...
Not an issue for the average 6 cyl taxi but it could be crucial for performance vehicles.

Just askin.