It appears that engine compartment pushed in on the Belaire thus instantly killing the dummy. The Malibu engine compartment stayed intact and didn't crush the dummy.
They fail to say why the driver of the 1959 Chevy would have died instantly. I know the answer -- lack of shoulder restraint seatbelt would have caused severe head injury as the head hit the steering wheel, IF the driver was even wearing it.
The big difference between these two vehicles after the crash is that the Malibu is totalled, and the 1959 Chevy just needs a little body work. Even the hood still looks good.

they just ruined a perfectly beautiful Bel Air...
