Yeaterday I gassed up for the first time since May 20, 1021.8 miles. 12.3 gals. The car said 87.6 MPG My calculator said 83.07MPG. That is a 5% diff. I don't trust a calculators results after a one tank average because there are too many variables, such as gas filler length, pressure, temprature, etc. Driving home from the station the temp was 110, no A/C, window down 4 inches, driving very careful the current MPG seamed "stuck" on 150. It stayed that way untill I got into stop and go traffic. When I got home it was down to 130.8 MPG after 16.8 miles. That didn't sound right so I checked the accuracy of my trip A 14194 miles and Trip B 38206 miles. Trip A car = 78.4, calculator =75.96. 3% diff. Trip B car =76.8, calculator =74.095. 3.5% diff.
I get better milage in the heat too. Maybe it's the summer gas and or better atomization.
I don't know how accurate 130.8 is but it's fun to brag about.