Anyone who thinks old cars were built tough should see this video of a 59 Bel Air being crashed into a 2009 Malibu: YouTube crash test
Apart from being a terrible waste of a beautiful 59 Bel Air, I wonder where they found one that still had all its frame strength - I would have thought that even in a dry climate, the frame would have deteriorated some. But just seeing the video shot from inside the Bel Air cabin, as the dashboard hits the seatback, suggests that a little bit more strength wouldn't have made a difference.
Not surprisingly, the Bel Air driver would have been killed instantly, while the Malibu driver would probably have a lower leg injury.
I looked up the specifications and, while they are probably measured different ways, the Bel Air curb weight was 3600lb and length 210" while the Malibu is 3400lb and 192" - so they're not as different as I'd imagine.
Andrew