The Big Three automakers are facing their worst environmental crisis since the 1970s. Even before the Kyoto accord, General Motors, Ford and Chrysler were saying they couldn't meet proposed emission standards.
Carbon dioxide is the biggest contributor to global warming.
The amount of carbon dioxide that autos produce depends largely on how much gasoline they consume. A car averaging 27 miles a gallon of gasoline will emit less carbon dioxide for each mile driven than a sport-utility vehicle that averages 20 miles to a gallon of gasoline. To meet the requirements, which would take effect in 2012, automakers would have to sell fewer sport-utility vehicles, minivans and pickups. Those vehicles are popular and profitable for automakers. The global-warming treaty is not automakers' only worry.