I think the reason we're all getting similar results is we're using the car around town and burning very little gas. In your setup, you can change whether the computer recalibrates when you fill it up or when you manually reset it. I think that could clear the issue. Mine is set to automatically recalibrate when I fill it (not very often). On a few short (about 50 miles highway travel) trips I've made in HV mode where the engine runs more, the average does come down to a little above 50 mpg.
This car has quite a few computers all working in harmony with each other. For this reason I named this car "WATSON".
I now have a Level II charger on my garage wall.
Windows tinted rear doors, rear quarter glass, & back window