120mph Crash Test

[Nammi]

looking at the deformation of the cars:

if a car crashes into a wall it deformes obviously. the time it takes to deform is determined by the velocity and well the make of the car or:the distance of deformation - t = d/v -> d = t/v.
also when looking at the acceleration, which is the change of velocity by the time dv/dt

two cars hitting each other may have the double speed of one car hitting a wall (from one cars point of view) but also double the deformation area / lenght.
so the acceleration for each car will not change since t = 2d/2v and therefor constant. but the acceleration will be multiplied by the mass of each car which could result in an unequal crashforce with unequally heavy cars.