This post is correct. It is not ERDTT. My 2012 Volt uses the ICE well above the ERDTT set point in the winter. I sometimes use MyVoltHold on a short trip. Otherwise, I just let the ICE cycle on and off. I think this behavior may have started with the software update a few years ago. I have 165k miles on mine and the car largely still functions well. Even with this behavior, the "gas mileage" is still good. I live in Austin, though. It may be worse in a colder environment.Do you park outside or in a warmer than outside garage? Many of these older Volts (including mine) will run on gas in cold weather even when its warmer than the ERDTT trigger point. Today my 2011 started the ICE 30 seconds out of the garage, even though the Battery range showed 21. The outside temp was 33 Fahrenheit and my 2011 trigger point for ERDDT is 26. It ran in gas 13 miles before switching finally to battery, then showing the range at 19. It sat parked but unplugged out in the sun for 3 hours, upon restarting was on battery and everything back to normal. I figure the 11 years old battery needs to be babied, so I use mountain mode a lot in winter, and if ICE starts immediately as it did today, I just accept that the software is accomplishing saving my battery. All summer long it was great with 27-32 miles range.