Yesterday evening my wife arrived back home with a 1.5 ev estimate remaining. We thought there might be a chance that I could drive it to work the next day to charge it (we have not installed our EVSE yet) without starting the ICE (but if it did start that would be fine since it had not been on for weeks and might need it). This morning the EV range showed 0 (it was a little colder than the evening but not remarkably so). But it did start to drive without the ICE. And here is one of the interesting parts. The curved bar over the speed on the dash that gives you an idea at how much power the ICE will kick in was very pessimistic. It was on eco (it's always on eco). The sold part of the bar (EV for sure) was less than a tenth of the length. But I live only 2 miles from work and on slow roads so I took it easy and stayed on EV. Then starting from a stop sign after about a mile of driving, the solid bar was gone and the ICE kicked in. And here is the other interesting part. After a half mile of driving with the ICE and starting after another stop sign, the little solid piece of bar was back and the ICE was off. It stayed off for the last half mile which included a climb up a four story parking deck. With the solid bar as short as it was I could not reach much more than 25mph, but the roads I was on were suitable for that. Nothing good or bad here, I just found it interesting. I am still enjoying leaning about the quirks (features) of the Clarity.
Thanks for your detailed observations. I'm usually well charged so I don't have much experience with a depleted battery. Given the Clarity's drive train, what you described makes complete sense. With a depleted (not really depleted but with low charge) battery, the clarity switches to hybrid vehicle mode. Because it does not have a normal transmission, the ICE cannot directly drive the front wheels but acts as a generator to power the electric traction motor and recharge the battery. If you took your car on the highway, the ICE would directly drive the front wheels once you reached a high enough speed (about 50 mph in my experience). You would know this when the little white "gear" symbol comes up between the ICE symbol and the drive wheels. Even on the highway, it would cycle between electric motor drive only or with assistance from the ICE depending on the conditions. It could be a bit disconcerting that the ICE can go on and off several times a minute but this is the normal way that the new Accord and Insight hybrids operate all the time so it's perfectly fine.