I loved American car styles from day one to sometime around the '80s. After that, we fell off a cliff. And not just with cars, but with damn near everything regarding our once great culture. Music, movies, tv shows, cartoons, comics, clothes, foods, drinks (egg creams, malteds, etc)...
Oh I love old (American) cars, as you can already see.
I think MOST things were ruined by the ‘60s. Everything (and yes, I mean about everything, even horse-racing and German Shepherds) went south after the ‘60s got through with them.
Still many good things, even great, but the ‘60s hippie culture ruined everything as a whole, most especially the politics for good.