Recommendation? Best/favorite knife to break auto glass?

I'm a retired FF/Paramedic and have broken more than a few auto windows, both in training and in extrications...

The tempered glass that makes up the vehicle's side/rear windows is easily broken by any GBD (Glass Breaking Device), be it a punch (Res-Q-Me), reinforced Tanto blade knife, and even a MT Scarab GBD. Those auto windows will shatter into many small cubes w/o large and sharp edges.
It doesn't take much force and a sharp *tap* should do it if using an able knife tip.

The Windshield isn't tempered glass and won't break the same. They are laminated Safety Glass and will resist shattering into cubes like the side/rear windows, due to a clear tacky resin between the plates.
To get access through windshields, usually a hole is punched in the upper corner and a saw is used to cut the windshield around the upper and side perimeters. There's lots of *new* and *improved* devices out there but many Departments use something like this: https://www.rescuetoolman.com/Quik_Kut_Vehicle_Glass_Tool_p/sku-art50012.htm

Be aware that if all the airbags haven't deployed prior to a forced entry into a wrecked vehicle, they can/will at any time. The forces in them can severely injure folks, especially someone leaning in through a side window and catching it on the side of their head. Even disconnecting the battery prior to entry can still leave sufficient charge in the capacitors of the Airbag system to fire them for a time afterwards.

Finally, GBD's also are not made to safely break plate glass (think house windows) either, especially for the general public. Good way to cut arteries and tendons. Use a high tech rock of sufficient caliber...
 
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As gzb stated, almost anything CAN be used to break side window class in a vehicle. I prefer a spring loaded punch. easily used with just one hand - punch point to one of the lower corners (right hand - lower right corner, left hand - lower left corner) and push - window shatters - window frame will prevent your hand from going through the shattered glass.

It is best to use the back of a gloved hand to knock the glass squares out of the way, but a shirt covered elbow will work.

While I have carried knives throughout my 27 years as an EMT, I have never used one to cut a seat belt - I have always used either a dedicated seat belt knife (hooked blade, sharp on the inside only) or traumas shears. Use of either means a much likely accidental cutting of the patient - always frowned upon to cut the patient.

The first tool I was taught to use for breaking a car window in an emergency was the radio antenna - back when cars and trucks had "real" antennae. Just unscrew the antenna and whip the little round "impalement prevention" ball on the tip at the window and "poof" shattered window.

The 2 things I have used knives on wreck scenes for the most -
- opening bags of kitty litter for fluid absorption
- punching holes in uphill tires to quickly increase the stabilization of a vehicle. Tow truck drivers and insurance companies get pissed about this, but I never really cared what they liked.

Oh, fixed blades only for that tire punching - punching a tire with a folder is asking for a cut finger and/or broken knife.
 
You can slash tires with a sak. Remember it's all in the technique. Locks don't matter. Or just stab away with a triad.
 
T.L.E. Sharp said:
Roll down the window and break it in the door? If you can roll it down why would you be breaking it at all? And if we've got time to deal with blankets and whatnot we can probably also wait for first responders with proper tools.

If I'm using a pocket tool to break a car window it's because someone inside is in immediate danger. No time for blankets.
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I am a first responder. If you are breaking glass it is better if it is contained in the door. You should also avoid showering people with glass. Don't over think what I am telling you. If it isn't applicable then use your brain. If I am told to take a door or roof off a car with rescue tools and the window next to the patient can be rolled down, I roll it down and cover them with a blanket.
 
Jhansenak47 said:
I am a first responder. If you are breaking glass it is better if it is contained in the door. You should also avoid showering people with glass. Don't over think what I am telling you. If it isn't applicable then use your brain. If I am told to take a door or roof off a car with rescue tools and the window next to the patient can be rolled down, I roll it down and cover them with a blanket.
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What does any of that have to do with a conversation about glass breakers on knives or carrying a spring loaded punch. Obviously if you can just roll the window down you will. And I'm still not understanding why you would roll a window down and then intentionally break it inside the door. What purpose would that serve?
 
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Thanks everyone for the valuable information. Doing my homework now! Finding EMT and fire rescue websites that sell dedicated gear that I had not been familiar with (most of it in keeping with the recommendations several of you have given.)

FWIW, this topic returned to my radar when my Dad sent me this (in case this affects anyone's opinions):

"IF YOUR CAR IS IMMOBILIZED DUE TO A FIRE, THE ELECTRONICS WILL PROBABLY MALFUNCTION...

YOUR ELECTRIC LOCKS & WINDOWS WILL MALFUNCTION! IF YOU SUBMERGE INTO WATER SAME THING! THERE IS NO WAY TO ESCAPE!

DOORS AND WINDOWS DO NOT WORK.

USE YOUR HEADREST TO BREAK THE SIDE WINDOW. NOT YOUR WINDSHIELD."

ETA: His suggestion was to use the pointed ends of the headrest to break the window and this got me thinking about the problem and what other tools might be good to keep on hand.
 
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Me and my dad tow junk cars and we think those brass spring loaded center punches are the best tool for such a job, they're cheap, they work, and you don't have to work about putting your arm through the window. He has a spyderco assist to cut seat belts and I use what ever I'm rotating thorough that week.
 
In my case it is a Benchmade strap cutter and I love the spring loaded center punch.

BTW, Victorinox has a fun video about their Rescue Trekker knife.
 
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