Camel, as I have already said, there is already a PZEV Jetta, Fusion, Accord, and others. The PZEV Jetta is EPA rated at 22/30, yet it creates literally no more pollution than the Prius. (Or, if it does, it's little enough to stay within PZEV guidelines.) Imagine that.

You are wrong about equal-mileage cars being equal-pollution. Hell, the ULEV 2005 HCH is more fuel-efficient than the PZEV HCH, yet it creates more pollution.

All other things being equal, reduced fuel consumption reduces pollution. But not all other things are equal -- how the gas is burned, the design of the engine and fuel tank, and the catalytic converter all work to reduce emissions independently of fuel economy.