Oregon and Washington, along with six unnamed Northeastern states, will likely decide to implement California's new 2016 tailpipe emission standards that call for a limit on greenhouse gas emissions. The states involved purchase about 1/3rd of the nation's new cars. This is quite a conundrum from a legal standpoint. The California Air Resource Board (CARB) has long been free to set its own emissions standards, and other states have then had the choice of either using the EPA or stricter CARB rules. But California has never been allowed to set their own fuel-economy standards, with the automakers arguing that this would limit the vehicles they could offer in the nation's largest car market. Any limit on C02 emissions is essentially a fuel-economy standard (with CARB's proposal requiring a mileage increase of about 30% over current federal standards), and as such it's a safe bet that both sides will be seeing a lot of each other in federal court before this battle is over. It'd be nice to think that cars would become significantly more efficient over the next decade anyways and make all of this a moot point, but the last 20 years should be evidence that this is not likely to happen.