This really does work – I tried it this morning. De-ice your car windows with a zip lock bag with warm water in it. I know, it went viral, but I hadn’t tried it before. It’s no slower than de-icer, even on really thick ice (ours was very thick this morning), and while, yes, the resultant water does refreeze if it’s still freezing temperatures outside, this much thinner ice is very easy to scrape off, and did so with the windscreen wipers this morning. There is a caveat of course, as widely reported. Don’t use very hot water, as you might crack the windscreen, just warmish, not hot, water from the tap. The water in the bag cools down of course, but it’s still a higher temperature than the ice, and still does the job. You don’t even need to use gloves, because the warm water in the bag warms your hands up. Amazing.