Well if you drive your car on roads that have salt and debris on them it sticks to the windshield. When it comes in contact with the scraper it scratches the windshield.
It's called windshield washer fluid. Try using it FFS.
Is that actually gonna clear a layer of ice off? Somehow I doubt it.
It doesn't
clear the ice off, but it does melt some of it such that it becomes hella easier to scrape it off. No more hacking away at it.
This morning it was was thick enough that a scraper was barely cutting through it, even when using one of the pointy edges. I had to use hot water to melt it.
I'd be worried about the windshield cracking from the hot water.
I'm not opposed to the windshield cover, but the fuel savings would be trivial given that an I4 burns through max 2L/h at idle - a 6 min idle would use no more than 0.2L - $0.23 at today's gas prices 'round here. I seldom have to idle that long any way, and then I get the benefit of being nicer to my powertrain (not driving off totally cold) and some heat inside. Time savings, I don't know...I'd think not since you'd have to fold it up afterwards, plus the added time of putting it on before you retire to bed the night before.
I think it's a great idea, but I don't see the use for my purposes.