California in the US has adopted the world's first plan to reduce the emission of green house gases (GHG) from motor vehicles. The new rules necessitate cutting exhaust from cars and light trucks by 25 per cent and from larger trucks and sport utility vehicles by 18 per cent in a phased manner. The California Air Resources Board (CARB) unanimously approved the rules on September 24, 2004. Earlier, when the CARB had unveiled the draft plan in June 2004, it was staunchly opposed by automobile associations but hailed by environmental organisations.

The first phase of the plan would require a 23 per cent reduction by 2012, and the second phase the full 30 per cent by 2015. Roland Hwang, senior policy analyst with the Natural Resources Defense Council, is upbeat: "The main point is that the US must get started in cutting global warming pollution. Once we break through the political logjam, automakers will find new and cheaper ways to cut pollution even beyond the reductions predicted.' CARB estimates in the draft report showed that the operating cost of vehicles meeting the standards would be so low that it would compensate for the actual increase in the cost of the vehicle itself. Required reductions between 2009-2011 will result in an average cost increase of US $241 in the category of passenger car/light duty truck