Some glass can be surprisingly strong to the extent that it feels wrong and unintuitive.

Not auto glass in my anecdote, but last year I had a medium sized aquarium (30 gallons, ~114 liters) where the bottom got broken. I didn't need to fix it because I had a bigger spare waiting, so I decided to break it apart to more easily package the glass into a safe container for disposal or recycling.

I was able to smack that thing on a wide flat surface with a HAMMER and have it bounce right off. They were really hard swings too. My biggest concern was how freaking loud the hits were, like I was going to disturb a neighbor in their house or make them think they heard a gunshot. My second biggest concern was that I was going to fling glass across the yard using so much force. I believe put it into a large bin or wrapped it in something before I got the courage to turn it up to 11 and break the fucker.

I think I used a 3lb drilling hammer too, which looks like a mini sledgehammer. Heavier than a standard claw hammer, just not very pointy.

I've not personally attempted it, ^ahem^ but AFAIK it's fairly foolproof —though my sources* also preferred to grind/scuff down the metal bits a little to help improve kinetic transference. Who knows. 😉

*: NYC alley cats, '97-'11^