Under normal use, the outdoor cover will not freeze to the car. The cover is made from woven polyurethane and is finished with a Teflon coating on the outside, which prevents it from freezing by itself.
However, if the car is wet under the cover, the moisture can freeze in freezing temperatures. Usually, this does not stick to the cover.
It is advisable to always apply the outdoor cover to a dry car, especially if freezing temperatures are expected.