>>Their logic seems a bit wonky. One car hitting a wall at 120 is not the same as two cars hitting each other head on at 120. Wouldn't the car have to do 240 to simulate that ?
>
>No. 1 car hitting an immovable object at 120 takes the full force, however, 2 cars travelling at 120 (assuming similar mass) would disperse the force equally between them, thus they would both take the equilivent of hitting the wall at 120 not 240.

That is correct if the cars are of same model.
Different mass and body structure of the involved cars will
lead to different absorbtion of the kinetic energy.
Just picture a truck colliding with a passenger car -
I don't have to call up a tank ;-)