It's heavily export oriented. When the world economy is growing, Germany is growing rapidly on all cylinders, as soon as it slows down, it takes a big hit.
VW does have problems in China (and Tesla is quiet strong there)
He's not saying Americans are the center of the world (I guess this is what you meant), he's saying America is a key market. It is, I'm European, but I would be damn stupid to not recognize America is almost as big as the whole EU.
Edit: And in average, richer.