The two biggest innovations of the 1950s were padding where a driver’s head might hit a hard surface, and seat belts, which as an option became quite popular. The industry made several more changes, based on *aircraft* safety devices, until the federal government leaped into the situation in 1965, based on Ralph Nader’s scathing, and inaccurate, portrayal of one model of car, culminating in the National Highway Traffic Safety Act in 1966.
The LBJ administration started to require cars have seat belts, but this had only limited effect until states started to mandate their use in the mid-1980s.
Car makers started offering airbags in the 1970s, but stopped because consumers didn’t want them. The government made them mandatory for drivers in 1989 and passengers a decade later.
In the 1950s, the death rate was 6 per 100 million miles traveled. This has dropped to 1.13 deaths per 100 million miles. But this is deceptive for several reasons.
1) In both cases, the majority of deaths are pedestrians, not vehicle passengers.
2) In the 1950s, the vast majority of vehicle-traveled road was lower quality state highway and local streets. The Federal Aid Highway Act of 1956 creating the Interstate Highway system radically increased the amount of vehicle travel on pedestrian free roads. The standardization of much safer roadways at the state and local level also radically lowered the number of fatalities. So to a great extent, fatalities decreased not due to safer cars, but to safer major roads.
So the bottom line is unclear, with some safety features contributing a lot to safety, while others, less so, some creating just marginal improvements. But other demands, such as ever increasing fuel efficiency, have strongly worked *against* safer cars.
In recent years, it has reached a tipping point, because lightweight economy cars are no match for structurally sound vehicles, and are just obliterated in two vehicles collisions with them. The initiative of the advocates of lightweight vehicles is to make structurally sound vehicles socially unacceptable, and eventually to have the government restrict their use.
I do agree the push for lighter vehicles is a bad idea. Small cars are great for urban driving, but are unsafe in high speed collisions.
One more thing. You would be surprised at how little difference there is in vehicle weight between comparable cars then and now. The older cars look heavier because they are longer.
About the same weight: