A minor crash in a 50s and earlier car would likely result in death or severe injury due to the lack of seat belts, lack of crumple zones, metal bayonets knobs on the dashboard, metal dashboards, etc.
Pre-50s is definitely going to be quite fragile, but it really depends what you mean by "minor". In a major crash, a modern car is going to be far safer, but in a minor one both the passenger and an older car are likely to survive with nearly no damage, whereas a modern car, although with the same outcome for the passenger, may be damaged extensively. Late 70s/early 80s bumpers were probably the best designed for this.
I am not sure about that. Seat belts were not mandated in the 50s so a crash resulted in significant passenger movement. Metal dashboards with bayonet knobs tended to cause significant damage based on my reading. I noticed that you put the link to the Lifeguard package in another reply but that was just a package available to some cars and was not bought in a prevalent manner by the public.
Pre-50s is definitely going to be quite fragile, but it really depends what you mean by "minor". In a major crash, a modern car is going to be far safer, but in a minor one both the passenger and an older car are likely to survive with nearly no damage, whereas a modern car, although with the same outcome for the passenger, may be damaged extensively. Late 70s/early 80s bumpers were probably the best designed for this.