Breaking a child or animal out of a hot car may save its life. We took to the junkyard to test out which worked better, a hammer or a window breaker.
The first rule of thumb is to hit the window in the corner. The middle of the window may seem like the obvious choice, but it is the strongest part of the window.
We used manual window breakers and were not successful breaking any windows.
When using the hammer, we were able to break all but one window, that window was tinted.
If the windows are tinted they are going to be extremely hard to break because the tinted coating creates another layer of strength for that window.