My case is that manufacturing vehicles is a public good. We can talk about restoring city centers to human beings and I'll agree with you all day, but if you want to make the case that motor vehicles, cars included, are themselves immoral, we don't share enough values to have a productive conversation.
So these companies, to provide this benefit, must comply with the law. Consumers have choice in what to buy, but strictly limited by price tag and availability.
Note that we don't have a cultural trend of buying cars with enormous rotating blades on the bumpers. It's not so much because this is illegal, as none are available for purchase.
The government decided, correctly, that the fleet should be more fuel efficient. All the reasons for this are good. So they did the obvious thing: imposed increasing taxes on gasoline.
Ok, let's back up: no, they passed insane regulations leading directly to the prevalence of SUVs and the increasingly hostile road profile of pickup trucks.
The law allows them less fuel efficiency if they make the wheelbase bigger. That's insane. Shall we apportion some of the blame to the car lobby? Ok. Sure.
Ultimately the government is responsible for the law, and the manufacturers are responsible for following it. End the insanity, and the problem goes away over a decade or so.