[hcknwscommenter]

Not necessarily. Much of the extra size is to increase the crumple volume. Those crumple volumes absorb energy in a crash, which benefits all involved in the crash. Raw weight on the other hand is an entirely different matter.

[jacobwilliamroy]

Is it physically possible for the energy absorbed by crumple-bits to be greater than the additional energy required to decelerate all the extra mass which the crumple-bits provide?

[remcob]

Yes, the energy required to make permanent deformations in a material is unrelated to it's kinetic energy.

[humbledrone]

I'd rather get hit in the head by a ten pound blob of clay than a five pound iron ball. (Preferably neither, though.)

[jacobwilliamroy]

I think I'd pick the iron ball? I'd have to feel the clay first.

[cma]

Would you rather be hit by a moving concrete wall or a moving concrete wall at the same speed but with 5 layers of cardboard boxes taped to it.