Another vote for the silicone. -Either as a spray or a stick. (stick is easier to control).
Not only will the silicone prevent the rubber from sticking/freezing to the doors. It also has a preserving effect on the rubber.
In my part of the world, winter is just around the corner. And we can get temps down to -25 deg Celsius. -We see the silicone sticks for sale at every gas station by now.
My 300E got 'siliconed' this weekend.