I drove my S90D from Twin Falls to Tremonton in January when the temp was literally 0F. I was in a hurry so I was going 10 over the speed limit which is 90mph. I charged to full which was about 285 rated miles at the time. Obviously the conditions were awful but I was still shocked that I actually had to take some preventative measures to be sure I made it. I didn't want to slow down since I was in a hurry, but I did kill the heat for a couple 15 minutes stretches. I think there is a slight downhill stretch before Tremonton so when I hit that I was fine and made it with like 20 rated miles to spare. So maybe I didn't need to kill the heat after all. But with temps around zero, I wasn't going to risk getting stranded lol.