Breaking Vent Glass

When put in an emergency situation where you need to break into your own car, you should try to not break the small side panes by the doors [quarter/vent glass]. This is the most expensive glass to replace on the car. The reason that vent/quarter/door/back glass is so expensive compared to a windshield, is that a windshield is a laminate while the rest are tempered. Tempered glass is made with heat in excess of 720°C or various pressures and other chemicals are used. Also, when cutting tempered glass, a special diamond cutter is used. Therefore labor and material escalate the smaller the tempered glass is.