...California...adopted a law last September that is the first in the world to require limits on so-called greenhouse gas emissions from passenger vehicles...the California law is being challenged in court by the Alliance of Automobile Manufacturers (AAM) and the Association of International Automobile Manufacturers...Jason Mark, clean vehicles programme director at the Union of Concerned Scientists...[said] the ''Big Three'' carmakers in Detroit -- Ford, General Motors and Chrysler -- are ''at the bottom of the heap when it comes to addressing greenhouse gas emissions"...Ford Motor did not have anyone available to respond to Tierramérica's questions. [also refers to opposition to the California law by Toyota, and to steps to reduce emissions by Hyundai Motor (part of Hyundai Kia Motor), Toyota]