...when ALL the energy contents per volume are accounted for (assuming constant volume, of course) it comes down to effective proportions of BTU content of all the fuels. Look up
Gasoline Gallon Equivalent on
GOOGLE.
...I've always associated
ether with "starter fluid" for cold diesel earthmoving equipment, but, yeah, it'll "burn" too.
...NOX supplies additional oxygen, which helps combustion and HP output, but not MPG!