Hard enough to not fly out accidentally but weak enough that people can break them on purpose so they're not trapped inside.
I think there's an impossibly thin line between making glass that's easy to break through on purpose, but hard for a high speed head to break through in an accident.
We have airbags, what if there was a low cost manual way to trigger a window break, potentially even without vehicle power?
I think there's an impossibly thin line between making glass that's easy to break through on purpose, but hard for a high speed head to break through in an accident.