i would be more concerned with heat from the sun shining in the car (cooking) your machine than worried about it being too cold...it will be fine in 40 degree temps. but put it on the floor, maybe with something draped over it to protect it from the sun or put it into the trunk.
i have a viking designer one and it has been in the cold for hours many many times...without problem...if it freezes you need to let it come to room temperature before plugging in and turning on. :thumbup: