Automakers say the Obama administration appears not to be wedded to the 56.2-mpg target for 2025 it floated last week and may be open to other refinements, according to Automotive News.

The manufacturers are pushing for a single national program while expressing concern in private talks with the White House that the standard may be too tough. They are arguing that no decisions should be made until new forecasts of manufacturers' technology, costs and sales become available.

Environmental advocates who had been calling for a 62-mpg standard expressed support last week for a target of 56.2 mpg, or annual increases of 5 percent after the 2016 model year.