[tjoff]

That is exactly what the crumple zone in the car is for though. You only have X meters of margin before you need to be at full stop. Assuming (dangerous to assume, yes) it does its job perfectly the most important factor becomes to react, that is to start the slow down as quickly as possible so you can utilize the crumple zone to max effect. I feel like flesh compression will mostly delay the impact rather than properly slowing you down (fast enough), which would be a bad thing.

That is in part also why it is so important to have a properly tightened seat belt and why we have explosives to tighten it up further when a collision is detected.