What happens if the Roadster is "cold soaked" at 5F overnight, the next morning the owner gets in the car, the batteries charged overnight.
The owner starts the car, turn on the heated seats, turns on the heater(instant heat), turns on the CD changer, some sort of heating mechanism will start warming up the batteries and by pass the cooling radiator, turn on the lights is early morning winter still dark outside. The Roadster has vacuum power brakes, an electric vacuum pump is operating to create vacuum for the brakes.