Some of it will go into the crumple zones, the rest will go into burning rubber and throwing passengers against their restraints.
The question is whether a person is better able to withstand being pushed from the back with rapid acceleration, or absorbing the energy of a collision.
I do not have an answer, but I'm very interested where I could find one.
You mention whiplash in another comment. Wouldn't you avoid most whiplash with a properly configured headrest?
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