I went for beer and when I left, I noticed my, arguably-brighter-than-the-average-lamppost, youngish neighbor was toiling with the frozen snow that covered his car.
I returned to find he had not made any headway, but had shed his jacket. It's not really cold, but well below freezing, after a day of rain, then snow followed by rapidly falling temperatures.
This punk had placed a special -made carpet remnant that he had cut to fit perfectly around his windshield and doors, presumably to make getting away quickly in the snow legions easier. It was frozen solidly into a crystalline rock which made it nearly impossible for him to breach the interior. He only had one small corner pried loose after half an hour. I discovered this and told him that the only way he will get that thing off was to start the car and allow it to warm up from the inside, but his (only other access) hatchback was broken and would NOT open.
Don't ever do that in Indiana. The horrible orchestra that becomes Indiana weather is NOT just one solo instrument.
He's going to be over an hour late to party with his friends.
I bought a black plastic sheet some time ago which was designed to cover just the windshield of a car that was supposed to make it easier to get the snow off. I wonder if it would have done the same thing, since there is usually a layer of ice under snow here, too.
It would, but you are the chemist.
Your plastic sheet is likely to be only slightly, if any at all, porous. A piece of carpet remnant, half an inch thick, is quite porous and very absorbent. You can most likely imagine the rock it would turn into after being carefully (form-fit a few weeks ago, for he is clever) applied to the top of his car (several times, he has done this, successfully) soaked with rain, covered with light snow (the light snow is what the guy was trying to protect against) then exposed to rapidly falling temperatures reaching the lower twenties.
It was welded to his car.