Seriously, this story isn't as funny as it sounds. It's a good thing they were able to find and kill that rat and didn't got attacked by it. These rodents may have some similarities to mice on the first glance, but are completely unlike them. Aside from chewing throught concrete (metal car body is nothing to them), they also can be agressive and carry nasty diseases, not to mention they're very though (the fact of surviving being thrown out of window of a moving car says something). I've heard about rats sometimes killing cats and even small dogs. This one, appearantely, wasn't that big (they didn't had to shot him and the poor officer still had his thumb), but still could be very dangerous. I'd say they were actually quite lucky.