The Federal Motor Vehicle Safety Standards have a lot to say on the strength, composition, and properties of glass in passenger vehicles. In addition to being very difficult to break, it must also be resistant to shattering and remain in place while experiencing some pretty extreme forces.
Automotive glass is not even glass really, it's more of a composite made up of layers of various transparent materials all designed to counter balance the weaknesses of the other layers. And windshields are bonded into the body of the vehicle with a very strong plastic adhesive.
I'll admit not keeping up with the standards, but back around ~2003 it was pretty common for arrestees in police cars to escape custody by kicking the rear window out from inside the car. It's held on by glue or something and pops right off the frame in one solid piece.
Cruisers now tend to have cages to prevent this.
(This is not a solution if the car is underwater.)
Sadly, no. Unlike some better fields, the auto industry is incredibly tight-lipped about safety and crash structures. If these in-formal standards were to get out... and if the public were to know how well the industry has cornered the regulators, creating pseudo-standards that technically conform to the safety protocols but functionally make zero difference to consumer/passenger safety... there'd be riots.
