[creesch]

How about a simple tiny safety hammer instead. The ones a lot of cars (at least here in the EU) are already outfitted with. As others have pointed out, any car should have such a hammer.

[trinix912]

I'd assume it doesn't do much with laminated (rear) windows. It would require way too much force to break them enough to crawl out.

Also, I've only seen those on busses, never in cars (I'm in the EU as well).