If California is really that concerned about greenhouse gasses, why don't they simply refuse to register those vehicles the state believes produce too much? California could very easily stop those vehicles that produce high CO2 from being driven in the state. They could refuse to register them, and they could even prohibit them from being driven at all, by stopping them at the border, or just ticketing any vehicles with high emissions. The state legislature can pass laws against the use of such vehicles. California owns most of the roads within the state, surely the state can regulate what vehicles are used. It already does, based on safety specifications as well as pollution specifications. It doesn't need to sue the car companies. It only needs to pass a law.

This looks like grandstanding to me.

This is an interesting 'strategy', in light of the fact that SUV sales increased last year by 12-17 % (depending upon the region). What communities and companies cannot accomplish of their own free will must become the subject of litigation. A law suit alleviates the guilt of the government and saves face for consumers who continue to buy high-emissions vehicles. This will work as a PR move whether the manufacturers are found guilty or not. California governor Schwarzenegger has pushed climate change and CO2 emissions to the forefront of his public activities and has gone so far as to suggest that the subject should not be an aspect of bipartisan politics. http://www.desmogblog.com/schwarzenegger-take-the-politics-out-of-global-warming Litigation knows no party lines. Surely the automotive industry should account for its slow response to lower emissions standards, but we shouldn't lose sight of who buys, taxes and registers those vehicles.