As announced last week, the Canadian government and the nation’s automobile industry signed a pact yesterday to reduce greenhouse gas emissions of their vehicles sold in Canada by 5.3 million metric tons—about 25 percent—by the end of 2010.

The new standards will force an unprecedented increase in gas mileage for more than one-third of the vehicles sold in North America. New York, New Jersey, Connecticut, Rhode Island, Massachusetts, Vermont and Maine have adopted California’s strict emissions targets.

With this mass of auto buyers now joined by millions of Canadians, the auto industry is under increasing pressure to adopt the new levels for all its fleets, rather than offering different models for the two different markets.

If Washington and Oregon go down the clean-car road, the momentum will increase even more. And that’s probably enough to flip the entire North American market over to cleaner technology. Feebates–powerful point-of-purchase incentives—can also play a key role.