"I've been keeping a lookout for a suitable test window. One day I'll go ang buy some from a wrecker (practice for the whole family)."

Suggestion: buy some from a wrecker but leave them where they are, and do it. The height, the frame holding the glass, etc are all going to affect entry. It's not the same just laying it down on the ground and whacking at it.

Since you want to learn from the experience, in situ is the best way. You may find out that breaking in the center and then pulling out the glass with the hook end of a pry bar is the fastest way to gain entry to a vehicle. Or not.

I tried to break the passenger window of a sports car with a 30" pry bar, and couldn't do it. It turned out that the best way to get in wasn't to break the side window, but to push the top edge inward, then reach in and unlock it. I couldn't have foreseen that in a hundred years until I actually had to do it.

Sue