>Consider hitting a brick wall. The energy of the moving car is all dissipated in the collision, leaving a mangled wreck.

That might be correct but it comes off as a smart-ass answer unless the course covered deformation, which I suspect it did not given it was a high school course.

A perfectly elastic collision would still be the same - the energy is still conserved and divided equally between the two cars.

Assuming the cars are of equal mass. If not, the heavier one will drive the other car backwards faster, and the energy will not be divided equally between them. But the sum will remain the same.

I’m pretty sure the basics were covered in AP Physics when I took it but have no idea what the curriculum was like when he was in high school. That said, I agree that it’s generally a smart ass answer but a) teenage boy and b) I would be incredibly unsurprised to learn that a child of academic economists who goes on to get a PhD might be the kind of insufferable high school student who reads ahead and makes sure everyone knows about it.

the head on collision has zero net momentum while the car hitting a wall has significant net momentum which must carry into a shockwave through the wall, which also absorbs some of the energy of the crash. This makes the wall collision significantly gentler at the same speed.