I live at 6500 ft elevation. Yesterday I drove up the valley to an elevation of 8,500 feet. An 18 mi trip. I left with a full charge (approx. 13 mi). What I expected to happen was after 7/8 miles I would have exhausted the traction battery and would be on hybrid the rest of the way. That's not what happened! Because of the constant climbing I was registering in the PWR range most of the way. The dash indicators were showing EV and ECO but the traction battery was dissipating very slowly. I arrived at my destination with 1.5 EV miles left. I averaged 43 MPG. A very surprising condition. On the way down I averaged over 200 MPG and re-gained 3 EV miles. It almost seemed that while running in the PWR range under load not much of the traction battery was being used. Anyone have an similar experience an/or explanation?