Thanks for your experience.
I am still working on calibrating it properly. In fact, just today, I went and looked at the forum/support/manual webpages to try and get it going right. My average MPG on the UG is definitely always more than the miles/gallons calculation (like 6-8 MPG more). I should record those numbers and reset it each tank like you have.
I wonder if the 30-40% load is a *relatively* universal load % across different cars (e.g. is my corolla the most efficient at 30-40% too?).