Pause for a moment and reflect a moment of the nature of fossil fuel (hydrocarbon) combustion and why the "global warming" gas CO2 is produced. When combustion is done, the carbon doesn't disappear. It has to go somewhere. Further, the amount of energy released by combustion (which controls gas mileage) is highest if the carbon ends up as CO2 (which is the lowest energy form of carbon available). So, when a car that burns gasoline produces CO2, it is working at its best. The same, by the way, is true for fossil fuel power plants, whether oil, natural gas, or coal: they all produce CO2 when working properly.
If man-made activities are responsible for global warming, then governments should set policies and enact laws regulating the burning of fuels. California Attorney General Lockyer's lawsuit, however, is merely a political stunt.