The problem is that the US market focused, thanks to insanely low gas prices (due to lack of taxation) on bigger and bigger cars, and Detroit did respond to what the market wanted - and fed that demand too, because they had an advantage in the light-truck sub sector.
Demand has shifted brutally because the impact of gas prices is much stronger in the US than elsewhere, and the Big 3 are weaker in the smaller segments - they simply haven't marketed their products as "no-nonsense" cars, and it takes more than a few years to change your product mix. In the long run, we're all dead. John Maynard Keynes
Not a single Japanese car: zero, none. Probably the only country in the world (with North Korea?). It was really striking. Europeans think a hundred miles is a long way. Americans think a hundred years is a long time.