I've just bought one of these: http://www.swedishicescraper.se/ This morning I had that horrid thin but rock-hard frost on my windscreen and it went straight through it, unlike the previous petrol-station one I had where I was out there chipping away at it for ages. They go for about £12 on Amazon, which is a bit pricey for a scraper but it's worth it for the time saved and it's nice and solid so it should last.