Thanks guys!
The Scangauge was a little high this time. I believe it's the E10 that messed up the calibration. I've been running straight gas, but we just lost that option in this area.
83.9 on the gauge, 82.4 actual.
I'll likely not be pushing it this far again any time soon. My mpg drops at the end of a tank. It gets tricky to restart the car, due to poor fuel pressure, so I use more engine-on coasting instead of off. The tank was at its highest of 84.8 mpg 100 miles earlier. If I can't beat the distance, it's better for me to fill sooner and use less fuel. Also, less possibility of stressing the dry fuel pump.