I drive a somewhat "old" model S 85 2014, and last week I did Montreal to Niagara Falls. That is a ~700km / 434 miles drive. Brace yourselves, it was -25c or -13F if you prefer (!). It gets worse, wind chill was at -37c or -34f.
My 0 % was indeed a 0, even with that extreme temperature.
So...