I am taking my LR M3 on a winter road trip. I am concerned about a stretch between superchargers of 280km. It is projected to be -20 when we leave, and -20 when we come home. Is this doable? A better route planner says I will arrive with 20% charge I am not sure I trust that figure with it being much colder. Unfortunately my CCS adapter is not going to arrive in time. Any thoughts/opinions? what wh/km or mile do you get on highway speeds on a freezing cold day?