I also am having the same problem with my early 2010 with 95,000 miles. I live in Oklahoma and noticed the lack of switching into EV and displaying full battery in cold winter weather some last year and now more of it this winter. Mine often goes 2 weeks without use. After about 20 to 30 miles of driving it starts running normally if not too cold. I have been attributing it to going into the HVB rebalancing procedure, either because of low temperature, long rest between use and/or weaking of HVB health. I had the air bag recall done last weak, but it was doing it before that so I can't blame it on messing with the dash removal. My dealer is dumber than a soda cracker about hybrids so is of no help. Helpful to know that I'm not the only one having the same problem, but still looking for a good understanding about just what is causing the symptons and a realistic fix. Does anyone have any experience with replacing the 12 volt battery to see if has any effect on this issue? I still have the orginal battery - coming up on 10 years this summer. Previous experience witth gen1 Prius and Tahoe 2-mode Hybrid is that 12 volt battery needed replacement after about 5 years. I also had my Fusion Hybrid throw a red wrech powertrain malfuction light while internstate cruising at 75+ mph in 100 deg F temps last summer. Took about an hour to get the red wrench, would go away when shut down and restarted - leaves no codes. I'm attributing it to excessive temperature somewhere in HVB package, but no permanent damage. Anyone else seen this happen?