> Light cars are usually more efficient. That's true, but US fuel economy standards don't actually require vehicles to be more fuel efficient in a direct way.

> Light cars are usually more efficient. That's true, but US fuel economy standards don't actually require vehicles to be more fuel efficient in a direct way. They require vehicles to be a certain fuel efficiency for their footprint. Unintuitively, while making a car larger doesn't make it more fuel efficient, it might make it better meet US fuel economy standards.