is a Standard that has support of the industry. Past administrations have tried to raise mileage standards, but often the auto industry has said "nope, we can't meet that", and refused. A huge group of players had to get together to establish these standards, and I don't think the lawmakers in congress had any part in this. It's a standard not a law. Those who support the Standard will work to achieve it.
An example is the Dictionary, it sets standards for spelling and word use. Not all follow this standard.
