Model cars: White House to auto companies: it's time to stop playing around. Jennifer Cheung/Corbis

At the Supreme Court, on Capitol Hill, and in state legislatures around the country, NRDC has spent years aggressively pushing auto manufacturers to increase the fuel efficiency of their vehicles and decrease emissions of greenhouse gas pollutants. So it was especially gratifying when, on May 22, President Barack Obama stood in the Rose Garden with a group of environmentalists, auto industry executives, and federal regulators to announce the establishment of strong greenhouse gas and fuel-efficiency standards for cars. This "historic agreement," the president declared, will "help America break its dependence on oil, reduce harmful pollution, and begin the transition to a clean-energy economy." On hand for the ceremony were the heads of General Motors, Ford, and Chrysler, all of whom have embraced the new rules, which will create greenhouse gas emission standards; these will be roughly equivalent to an increase in fuel efficiency to 35.5 miles per gallon. New car models will emit, on average, 30 percent less greenhouse gases than current models. Roland Hwang, NRDC's vehicle policy director, called the agreement "transformative."

It was a long and winding road that led to the Rose Garden. Key landmarks along the way included the Supreme Court's 2007 ruling that classified carbon dioxide as an air pollutant under the federal Clean Air Act (NRDC was a party to the suit), as well as the Environmental Protection Agency's recent determination that global warming pollution is indeed dangerous to human health and the environment. A shift in the economic climate also played a role, according to Hwang: two of the most recalcitrant auto companies, GM and Chrysler, discovered they had much less political leverage to fight greenhouse gas and higher fuel economy standards given their reliance on federal loans to stay in business.

After his day at the White House, David Doniger, NRDC's climate policy director, noted, "We'll have cleaner cars nationwide that meet California's landmark standards. We'll drive cars that save us money every time we fill up at the pump. And we'll help the auto industry get back to health by making cars that make sense in a world of higher oil prices and ever-growing concern about global warming."