although big and heavy, old cars were not engineered with crumple zones surrounding the 'cage' area of the driver. modern cars have a strong cage area, while other areas are designed to absorb energy upon impact.
one interesting old vehicle, the original VW bus. in a front end collision, the first line of defense are the drivers legs! obviously this would never fly today.
because drivers feel safe in their modern cars, just another good reason for motorcyclists to be extra cautious riding around all these missiles