[redpoint5]

Air quality mostly improved due to catalytic converters being mandated and fuel injection. The government has authority in setting acceptable limits of pollutants, but they certainly shouldn't be micro-managing how to achieve these results.

The point of fuel efficiency standards is presumably to lower emissions and dependence on foreign oil, but often the result of increasing efficiency is increasing consumption.

The right way to reduce emissions would be to manipulate the price via taxation to achieve the desired emission levels. It allows the consumers to find the most efficient way to achieve those results and leaves little opportunity to creatively work around the rules.

Of course, this is too easy, and can't really be leveraged for political purposes. Politicians get elected by being hard on those "evil" auto manufacturers, but would be despised in those same states for increasing taxes, which is effectively very similar.