07-24 car window glass

[Image above] Tempered glass and laminated glass are both used as side windows in cars. Only one can be broken with common vehicle escape tools. Credit: Two Cats New York Video Production, YouTube

When shopping for a new car, what is the first spec you consider? Fuel economy? Engine power and torque? Price?

Probably few people would list “side window glass” in their top five. However, a new study by AAA may change that assumption.

“The majority of vehicle side windows are made from tempered glass, which shatters into small pieces when broken,” AAA researchers write in the study. “But an increasing number of vehicles are being built with laminated side window glass, which is stronger, quieter and much more difficult to break.”

Laminated glass is stronger than tempered glass because of its sandwich structure—a plastic film, typically polyvinyl butyral, placed between two layers of glass. Discovered by accident in 1903, manufacturers began using laminated glass in automobile windshields in the 1920s. Today, many countries, including the United States, have laws requiring the practice.

More than a decade ago, it became apparent that automakers were starting to use laminated glass often in places besides the windshield, particularly side windows. The reasons for this vary—lesser chance of occupant ejection, more UV absorption, theft deterrent—but the strength of laminated glass is also the driver’s downfall in accidents requiring quick escapes, such as vehicle fires and submersions.

AAA examined a selection of six vehicle escape tools (three spring-loaded and three hammer style) to determine their effectiveness in breaking tempered and laminated vehicle side windows. Of the six tools, AAA researchers found only four could shatter tempered glass and none could break laminated glass, which stayed intact even after being cracked.

Though ejection accidents are more prevalent than vehicle fires and submersions, AAA advises making note of which windows are laminated in case of an emergency. You can determine the type of glass your vehicle has by looking for a label located in the bottom corner of the side window. If the label is absent, you can contact the vehicle manufacturer or check out this list of vehicle models with laminated side windows compiled by AAA.

For a demonstration of the difference between tempered and laminated glass, watch the video below by Two Cats New York Video Production. They test two popular vehicle escape tools—the resqme and the Lifehammer—on both types of glass and demonstrate the ideal place to hit side window glass to increase chances of breaking.

An important finding from the AAA study is that spring-loaded tools are more effective in breaking tempered windows than hammer-style tools. So keep that in mind when purchasing a vehicle escape tool!

Credit: Two Cats New York Video Production, YouTube