To add to what I posted about the civic, and in response to what Dave mentioned...Yes, the crumple zones in the frame are supposed to absorb the impact and keep it from being transmitted to the passenger compartment. I could not believe it when I saw that the front "crossmember", the real bumper in essence, behind the plastic, was sheared THROUGH by a trailer hitch! Didn't pull the framerails in, didn't move anything, didn't even push against the plastic bumper cover enough to split it, but sheared right through the damn crossmember from a 5mph impact. A 15 mph impact into a tree broke the engine loose and pushed it back against the firewall in the same year civic (04).
I certainly don't know much about crumple-zones or the engineering behind what Honda is doing with the passenger capsule, and it must be more than decent enough to pass crash testing, but thinking as the aerospace engineer I am, I would imagine the front crossmember of those things should be beefy enough to keep the force of the impact in the frame rails and respective crumple zones, not allow it to pass through to the engine and shove that around. If a 15 mph impact was enough to break the engine loose and get it against the firewall, I can't imagine what a 45 or 50 mph impact would be. I'd have 4 cylinders of fury in my lap!
Sorry, I am just not impressed with the engineering in some new cars, Civics in particular. The benefit of a new car that is a throwaway after a crash is supposed to be that you are totally protected from anything. I don't see that.