In my university physics course, we did a project where we made our own physics models of car crashes and compared with crash tests and statistical data about r

In my university physics course, we did a project where we made our own physics models of car crashes and compared with crash tests and statistical data about real-life crashes. Our conclusion at the time was that crash test results matched our models of collisions with identical vehicles of opposite velocity (i.e. a head-on collision - the most complex case we could solve analytically), which, if you work it out, should come out the same as the normal force when hitting something stationary like a concrete pillar. In this case crumple zones are the most important factor, as they allow you to decelerate over a longer distance. The real life data crash reports though matched the result we got from simulations (which is what we resorted to when the models got to complex to solve analytically), in which case by far the most important factor was the weight of the cars involved in a given crash. Whoever is in the heaviest car will tend to win the game of conservation of momentum. Kind of a sobering conclusion tbh.