Well, a lot of historians say that the USA's economy flourished post-war not necessarily because they "won" it (hard to define concept these days), but because everybody else's manufacturing infrastructure was completely flattened.

Why do you think the USA automobile market exploded post-war? It's because the two biggest automobile manufactures - Germany and Japan - were flattened to smouldering ashes and took around 30-40 years to recover.

That's why the USA auto industry declined on an enormous scale after the 80's, because in the end the USA was never automobile king. There was never the "good old Detroit days". It was just a temporary market vacuum that the USA capitalised on, while Germany and Japan, who simply were better at making cars (debatable of course, but they make more money and that's probably the most reliable metric here), were rebuilding their entire country from catastrophe.