Wonder what big brother’s plans are when people start raising cain over this. Even the most stupid useful idiot has his limits.
Just a guess but I think that the average American simply flouts the law. They'll keep their old cars on the road. Disconnecting advanced systems (emissions, electronic ignition, etc) as they fail. A whole black/grey-market industry will spring-up to keep older cars on the road. Gypsy garages, too.
Then the "ball" will be in the government's court. Do the ignore the violators? They probably will if they are confined to favored minority groups living in no-go areas where regulations are already being flouted. Or do they get agressive with rolling inspections? If that happens then you're going to see sparks of violence.