does anybody use crushable tubes to absorb inpact forces?

i was just thing about the crushable areas of unibody cars.

i was thinking about hydroforming.

machining a hydroform die to allow a piece of mild steel tubing or rectangular box to be hydroformed so it looks like a wavelock rod bolt. this will allow this section to crush and absorb impact blows.    this will lessen the impact on the driver and reduce the amount of frame that needs to be replaced.  

Interesting idea. Anytime you can absorb some of the impact energy in a crash before it reaches the driver, it has to be a good thing.