Japanese auto companies are subsidized by their home countries. Japan has block access to their markets for years.
This is an thirty year old story that just won't hunt any more.
1. Foreign Labor is cheaper - Well, Japanese companies build many of their U.S. Market cars in the U.S. - Accords in Ohio, Nissans in Tennessee, Toyota trucks in Texas, etc. Their labor costs are lower because none of them use UAW labor. If you really think that health care is such a big advantage for overseas companies, then why is Hyundai (a Korean company) building a new plant in the U.S.? That old whine about the governments subsidizing foreign car makers health care costs is just that- an old whine.
2. Japanese Keep U.S. Cars out- I was just in Japan two weeks ago; spent some time on Kyushu (the major southern island). There were lots of foreign cars. BMW's were the most common, then Mercedes, then Volvos, followed by VW's and a couple of Jaguars. I did see one Caddy, one Buick, one "Toyota" Cavalier, and a couple of Camaros.
The import barriers have been down for years.
The problem is still that traditional American cars are even less desirable on the tight, crowded roads of Japan that they are in the U.S.
Ford (Jaguar, Volvo, Land Rover) is doing quite well in Japan. Of, course, all those cars are available in right-hand drive - a handy little feature for Japan, which GM can't be bothered with.