Quality

All I did was take the DOT numbers from that chart and 2022 article.

[12.2 yrs (2022) - 6.5 yrs (1972)] / 6.5 yrs = 87.7% increase of average age of vehicle on road.

You are preaching to the choir brother. I'm NOT saying new vehicles don't last longer than the old ones. For sure, YOU feel you are getting a lot of bang for the buck.
But.....I bought a new Ram 3500 Cummins pickup in '95, cost about $30,000. It has 225,000 mi and runs like a top. No pollution BS either. Nope, it has no GPS, but you know what, I can read a $5 roadmap . A new one today is what??? $70,000-80,000?????
I bet like you say,,, IF you figure a 69 RoadRunner at its price new back then at $2900 with the miles it gets before being woreout and lets say any MODEST auto new today, the new one might well be more cost effect as to miles driven before wearing out. Like 125,000miles vs 350,000. But if you figure what $2900 in worth today calculated from 1969 the figure is what????? I ain't smart enough to know. A smart guy will google a chart!!!!!:steering::steering::steering::steering: