Probably because they stay on the road and out of the shop, come equipped years ago with what GM is just now realizing should be included, have a nicer ride, are quieter, smoother and all around better car than what GM can only dream of making.
Their new retro look trying to save themselves is asinine, like clown cars on the road instead of in the carnival.
No I don't own Jap, used to, now drive a German car. American cars are basically junk and why the big three are going the way of the airlines, down the crapper.