Now as politicians battle over the right to gain state control on vehicle carbon dioxide emissions, California legislators arelooking to expand upon their intended greenhouse gas controls. The original plan outlined adjustments from 2009 through 2016, but the revised outlook will shift focus up to the year 2020, which lines with the target date of the federal regulations. The major difference is that the California Air Resources Board believes cars and trucks should average close to 44 mpg by 2020. That breaks down to a 50.8 mpg car and small truck average and a 33.5 mpg average for vehicles tipping the scales. Considering variations across the country it's estimated to be an average of about 40 mpg for the whole of the United States. It also makes for an enormous 62-percent improvement upon today's vehicles.
[Source: Automotive News - Sub. Req.]