The debate between embattled auto manufacturers and environmental groups continues today, with environmental groups urging the government to speed up federally mandated fuel economy requirements. The proposal calls for the federal goal of a '35mpg standard by 2020' to be moved up to 2015, and naturally auto manufacturers are opposed to the plan as they struggle to cope with development costs associated with the stiffer standards. Central to the debate are the 2008-2011 requirements for light trucks, which a U.S. Circuit Court of Appeals ruled were 'fatally flawed' last year.

The debate was held at a hearing by the National Highway Traffic Safety Administration as part of the court ruling. The NHTSA's current standard of a fleet-wide avearge of 31.6mpg by 2015 is based on government forecasts that fuel prices will fall to around $2.40 per gallon by 2015, a fact that was an issue of contention during the hearing, reports the Detroit Free Press.

Several groups commented on the fact that this figure was a rose-tinted view of the future, and that fuel standards should be imposed on a worst-case scenario basis.

The Alliance of Automobile Manufacturers stated that the proposal called for by environmental groups failed to take into account the costs associated with achieving the goal, and that it was not likely that it would be possible to improve fuel economy so drastically in such a short time across the industry. The Alliance represents General Motors, Ford, Chrysler, Toyota, BMW, Porsche, Mercedes Benz, Volkswagen, Mazda and Mitsubishi.