It'll depend on more than just a tune. Different factors like using e85 mixtures will skew your results. Someone who uses the same tune with different fuels will have different fuel efficiency.
Yesterday someone posted that they get about 280 miles per tank with a 30% e85 mixture.
I get about 345 miles per tank running 93 octane alone.
Both of us are using a JB4. (he probably logs more smiles per gallon)