Try some of the dedicated windshield punches. They are small and very effective. In the Coast Guard we had boat and aircraft axes and our personal knives. We had to smash through plexiglass, wood and fiberglass, cut the occasional line or fishing net. I went through the AF survival knife, an early British MOD4 and eventually settled on a German Linder sheepsfoot with detached marlinspike ( The sheepsfoot blade was legislated into existence to stop seamen from knifing each other well before vulnurable liferafts.) The marlinspike proved very effective at punching starcracks into plexiglass with a following blow from the butt or bladeback ( depending on how scared or pressed for time we were.)