My wife and I semi-regularly drive from the Reno/Carson City area to San Francisco and back. Even the worst passes around here are only uphill for about 10 miles or so at most. Those tend to drain the battery a good bit, but never empty, or forced to run only on the ICE. I think the lowest I've seen it was 2 bars going up US 50 to Lake Tahoe. The San Francisco to Reno drive (San. Fran. being at approx. sea level, to a peak of around 7000-8000 ft. IIRC in Donner Pass), has never been an issue for the battery or the car.
I've driven the I-5 from the SF Bay area down to Los Angeles across the infamous "Grapevine" without any problems. I've taken the car into Sequoia National Park from the southwest and exited to the northwest which includes some very steep terrain. I've crossed Rt-152 Pachenco Pass (not that steep but I've done it a number of times so I coould watch how energy managed worked) and crossed the Serrias on I-80. None of these had me down to just the ICE. The management of the HV battery State Of Charge by the ECM is fantastic. I've purposely watched the Energy display of the MFD and you could see the SOC gradually dropping as demand for power increased but then as the steepness of the climb was reduced you would see the SOC start back up. Yes, the ICE was running hard all the time but when it wasn't needed to push the car along it was pushing amps back into the HV battery. I was impressed! I'm hoping to take the car across the Contenental Divide this Summer via Monarch Pass and then returning via Durango/"Four Points" and the southern route. If it runs out of HV battery then I guess I'll be pushing someplace along the way.
