I'm at almost 70k on the original 2014 battery.
Last winter, which wasn't as cold, GOM range was 85 and was accurate.
This winter, several degrees average colder, GOM range is 82-83 and is accurate.
I am driving 60 miles/day, five days/week. I run the heater on Normal, and use the seat warmer.
An interesting aside: I now pick up a carpooler for three out of my five days/week commute. When he's in the car, I have to turn down the heater about 2-3 degrees. That was unexpected. I make him drive on the return trip in the afternoon, he drives quite a bit faster than I and we use the carpool lanes, so closer to 70 than my usual 62. Could have something to do with the slight drop in GOM range.
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During the recent snow days, I drove the M3 because it's AWD, and while it's more comfortable (much more even heating, for example), I would burn 100-120 miles of GOM for a 60 mile commute. Of course, that's in colder weather and driving in snow & slush and slow traffic (=more heater runtime), but still . . . . good thing it's got 310 mi. range. I have it charge to 260 mi. max.