Originally Posted by
segfault
Yes, Mythbusters tested the center punch and found it to be very effective. They also tested several scenarios of cars falling into water and found them to be marginally survivable at best, and the worst case, with a car tumbling in flood water was deemed not survivable.
You can break a window but you have to get everybody out of the car, in dirty, possibly dark conditions, before they drown.
Its a mess.
One of the things Mythbusters found was that cars seldom sink right side up - they tend to flip over. Although Adam Savage (one of the MB hosts) was able to escape from the car when upright by waiting until the car flooded and the pressure equalized, when it was upside down he became sufficiently disoriented that he needed to take the emergency breather from the rescue driver in the back seat before he was able to escape.
After watching that episode, I went out and bought several of those rescue tools and put on in each of my vehicles...