I have kept track of mileage and amount of fuel burned. Last fill was at 360 miles and forced in a full gallon (actually over-flowed a bit). Today at 441 miles another even gallon, but not completely to filler neck.
So
1 gallon plus about 1/16 (8oz / 0.062 gal) = 1.062 gal
81 miles divided by 1.062 gal = 76 MPG
First 7 tanks were 0.66, 0.88, 0.98, 1.1, 0.94, 1.0, and 1.0 (today) = 6.56 gal
So about 67 MPG over first 440 miles. Still beats car by far ;~)