If your regen is anything like my old Prius was (and I know it's a lot more) then I wonder what your watts/mi was for the 100 miles of downhill after Donner Pass on the way home. Was it negative?
180 wh/mi from truckee to sac area. I charged for 3 min at truckee So my trip reset. 18kwh to cover 100 mi.
truckee to the top of the hill (boreal) was probably 10 miles? Then 50 miles ish downhill. and another 40 to sac area.