The auto industry and its advocate, House Energy and Commerce Committee Chairman John D. Dingell, D-Mich., accepted achieving a targeted average of 35 miles a gallon for each carmaker's fleet of new U.S. vehicles by 2020, The Washington Post reported Thursday.

However, automakers reportedly gained concessions that would extend fuel efficiency credits for flexible-fuel vehicles and creating separate mileage standards for cars and light trucks.

Negotiators reportedly are leaning toward language that would require the first "advanced biofuels" derived from sources other than corn be used in 2013, the Post reported. Current Senate language would require at least 3 billion gallons of advanced biofuels be used starting in 2016.

House of Representatives and Senate conference committee members have been pressured to resolve differences between the two chambers' versions so it could be voted upon next week.