I'm suffering in near identical temps, 25-30° currently. Showing 30 miles of range now, and just barely getting that. I keep heat on comfort, 74. My range took about a 4 mile hit when I replaced tires too. Lord knows what snow will do! Turn off your auto-defog if it is on, it's a real range killer.
20 mile range is normal for my 2012 with comfort heat when very cold (teens degrees F) is normal. Worst I have seen is maybe 15 miles (high of 0 F). I have ERDTT disabled (otherwise you probably won't get much worse than 25, but add in substantial amount of gas).
PS, I notice you are using ERDTT, when the engine starts turn to fan only or eco as you can use its heat instead. Comfort means you will use both engine and electric heat, but the engine is the more efficient heat generator. The car is smart enough to blend them, but I disabled ERDTT for that reason, my electric range was about the same, but I didn't burn that 1/3 gallon of gas.
PPS what year is your car? If it is 2013 or newer you can turn the ERDTT down to the very cold setting of 15 degrees, which means your range won't be better, but on a day like today you would save the gas.
I am hitting the 20 mile range too and use comfort, defog, snow tires and drive short ranges. ERDTT actually helps improve range even though you burn gas instead. It will come back when the temps are in the 50's and higher.
2013 with very new Continental TrueContact EcoPlus tires inflated to 42psi
mid 30's F ambient temperature
Rolling hills commute of 39 miles.
Cabin set to Comfort and 72 degrees.
Since I will over-run my battery every day, in each direction I use this technique (see post #8), and my average actual battery range has been holding pretty steady at 29 miles. Just fyi, at start the guess-o-meter has read anywhere from 21 to 31.
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