Talked about a long time ago. When I got my Clarity, like many I think, the traction battery was on 0, and likely been that way for long time. The dealer told me they knew nothing about Clarity and didn't want to sell it, but it came with their allocation of other cars. Anyway, maybe related maybe not. Even my test drive did what we call angry bees. SOC was likely near 0%. I did get $2500 off MSRP and bought the car. Took it home, charged it, and of course the electric experience is WAY better. Sad that the dealer made no effort to maintain the battery state.
Anyway, first about six months of ownership, I'd charge the car fully and drive to PDX (about 109 miles from Eugene, all flat interstate) and my EV range would drop to zero even with HV on all the time. I didn't know this wasn't normal. HV is supposed to try and maintain SOC. My SOC routinely went to 1 bar on the EV range bars, which is also anomalous. Most Clarities when they get to 2 bars stop, and the car automatically does hybrid mode. Nothing doing on my car. The engine would rev like it was going to go ballistic. Anyway, lots of behavior suspect few on these forums have ever seen. For example, my Clarity could never do 'gear' mode where you see the gear icon in the middle of the energy info screen.
Kentucky Ken on these forums (now a few years ago) asked me to reset my car by removing the 12v negative terminal, then replacing it. While this doesn't actually hurt anything you do see scary warnings for a few miles. After doing this once, my car started showing the gear icon on straight drives (like I5) and amazingly now mostly preserves SOC when in HV mode on the highway. I lose a bit even when not stopping, but say never more than 10-30% of beginning SOC if I'm religious about keeping it in HV mode. I also now never let EV go to zero. I've learned to use HV Charge anytime my EV range gets low.
Car's been great, works pefectly now (or as perfectly as it can and good enough for me). I get good gas mileage when in HV mode (~40mpg on average). My commute daily is fewer than 25 EV miles, so I can mostly go all EV although do burn gas in the winter time. My all-EV range is about 22 miles now, 5 years in.
-Dan
PS: I do think even post-reset, my experience isn't same as everyone else. I do need to 'train' others who drive my car. That is to say, I have a piece of paper on the drive button that says 'press HV' before starting out. It keeps them from having a bad experience with my car and is just simpler. I play the game of using as much EV-only miles as I can, but don't expect anyone else to. My car has never been "OK" running on 0 EV miles, and still isn't. Luckily relatively easy to avoid that.
One last thing: Not willing to test 0 EV even for "science" sake. I think it literally hurts my car to do so. That's off the table now. I just don't allow it to ever happen.
I have no other explanation.