Funny, I had a similar experience recently. A friend accidentally locked his keys in a running vehicle (a Ford/Mazda extended cab truck). Temp was -23C with windchill below -30C, which made it interesting. My friend had been trying to break the passenger window also (he's no wuss, ex-Air Force survival instructor and heading toward his 50th full marathon). He tried it with a metal snow shovel, then with a landscaping rock the size of a basketball. The window would not break. I showed up, and my 3/4 length axe would probably have done it; but we ended up using a Cold Steel shovel to pry/cut the goo and seal holding the rear side window in place. It took two of us, reefing on it with everything we had and expecting it to shatter in a million pieces at any second. But it came off without a scratch. I couldn't bloody believe it. I need to re-evaluate my notions about exiting a trapped vehicle.