I was able to go back and this time record mileage. At 2:00 AM, I was able to run a 50% power run too:
power miles MPG mph
100% 1.5 23.8 35
_75% 1.5 25.3 26
_50% 1.5 22.2 16
On the descents, I simply put the car in "B" and let gravity and the spinning engine do the rest. But I noticed the battery fully charged and the top bar, slightly pink, was illuminated.
I returned to my starting point, about a mile away from the base of the hill and the battery was still fully charged. On the second run, the battery charge still showed full as I approached the base of the hill. I suspect this is why the middle run showed exceptionally high mileage, a battery boost.
For the last run, I used "EV" mode to bring the battery out of the 'pink bar,' full charge and then used regular "D" to approach the hill. Until there is a standard way to normalize the battery charge, I won't be able to trust this data.
To handle the battery energy contribution, we need to measure the traction battery current. Then comes the challenge of trying to use the charge/discharge energy flow to compensate for the altitude and distance.
Bob Wilson