In the 60's manufacturers didn't care about aerodynamics, and they made big cars with big engines and terrible mileage. After the oil crisis, car and engine sizes shrunk and aerodynamics mattered.
I do find it always very odd how ugly the late 70's until early 90's period is. Fashion, architecture, product design, even hair styles. Almost everything looks awful. It's not just fashion, because you can pick designs from any earlier period and they look ok if dated, but that 20 year period from the mid-70's onwards is just so ugly. (Although undoubtably someone will be by in a bit to tell me how wrong I am and how beautiful that period is...)
I think it's a side effect of the baby boomers. In the 50s and 60s they were young and learning the ropes, so style tended to be fairly similar to the old. By the time the 70s roll around the old guard is retiring and these designers are now free to experiment wildly. Stuffy and boring is out, flashy and exciting are in. There is a whole generation of young adults driving the market.
Then the 90s roll around and those designers are getting older and realizing that most of the experiments didn't pan out and that there is some value in the old and boring.
I do think this is one big reason. Waves of people getting to act on the world. Also I'd add another factor, society feeds on drive, and younger people are hungry by default, so new projects will benefit from having them. I can see that in all new real estate work in Paris; it's all very very weird design (too sophisticated, too shiney, discontinuous, unintegrated) that I'm pretty won't age well at all. But that's how new buildings were done.. people needed the "escape valve" of youth to let the energy flow somehow.
I do find it always very odd how ugly the late 70's until early 90's period is. Fashion, architecture, product design, even hair styles. Almost everything looks awful. It's not just fashion, because you can pick designs from any earlier period and they look ok if dated, but that 20 year period from the mid-70's onwards is just so ugly. (Although undoubtably someone will be by in a bit to tell me how wrong I am and how beautiful that period is...)