Hmmm … my memory goes back to 60's although I can't recall much of 70's. You used to see rustbucket junkers EVERYWHERE on the road and you don't see them that much anywhere. Certainly not like before. I would say vehicles have improved greatly in the rust department. Pretty sure they made a lot of improvements in corrosion avoidance and that's why the cars you see running down the road look SO much better AND Ziebart undercoating became generally known as "not needed". Vehicles are a lot more reliable now too are they not? My 2014 Expy doesn't call for any scheduled maintenance until 100K. There was a time when 100K was getting to be the lifetime of a vehicle was it not? Huge safety and gas mileage improvements also. We used to have metal dashboards for example - OUCH! Corrosion avoidance, safety, reliability, gas mileage, power, transmissions, tires, a/c, traction, anti-lock brakes, etc … seems like everything is better than "the good ole days".
I would never try to convince you of anything but IMHO collision safety has a LOT to do with "crumple zones" and "energy management" and "airbag" etc. vs mile of iron & steel in front of you.
You have to go back even further to get into the good steel originally. It seems that since cars were first being made in this country they were very thick metal and durable up until the 70s. The old ones were thick and lasted a long time with or without undercoating.
It was right in the mid-70s when they started rusting terribly. I have heard a lot of people blame cheap quality Japanese steel but I don't know if that was just foreign or import bashing or not.
But we must note and remember that cars were very high-quality before that all started.
Now once they start arresting terribly throughout the 70s and 80s it was later that the improvements came. Better prep in the paint department better sealing and better paint had a lot to do with it and I know they talked about some galvanized rust protection. But by the early 90s ziebart's and undercoating rustproofing was starting to disappear as an industry As you mentioned.
They also started using a lot of plastic like bumper covers and plastic on rockers and cladding over doors bottoms. This made them last longer and even when the rust did get behind it it's still look good for many years.
Unfortunately, I think it's starting to get worse again. I don't know why, could be the liquid brine that they use instead of salt. In the old days it was sodium chloride and then I can commit to calcium chloride and now who knows.
But it seems that cars from 1990 or 92 up until 2005 or 2006 or so held up quite well. It seems the new ones now are starting to get rust problems earlier.
On the safety, you put crush and crumple zones in the same category is airbags. They are sometimes but my original post is to the fact that if you had one of the big old Landyachtz with the huge length of hood and large engine up front and big beefy still frames and strong bumpers THEN added the airbags and the same quality of seat belts as we have today, I think those cars would well outshine the newer ones in the crash tests for occupant safety.
They were also cheaper to repair because you didn't have to replace so many parts or so much in the same type of impacts.
I want subscribe to the theory that everything on cars is better now because of Simply time, progress and Technology. It's always a give-and-take. I certainly wouldn't want to go back to the days of carburetors even though I love a good hot rod with a carburetor and headers and loud exhaust Etc. But I do miss some of the largeness of some of the cars and comfort and some of the styling of the old ones. Other things I certainly do not miss. Remember how bad they were about having big heavy doors even on two-door cars with no frame around the window. They were weatherstrip whistling nightmares even if they didn't leak in the rain. Then there's lots of people still pissed about the disappearance of the small wing window. Lol
