The U.S. EPA and the NHTSA (National Highway Traffic Safety Administration) are proposing specific rules to implement a Heavy-Duty National Program to reduce the greenhouse gas emissions and increase the fuel efficiency of on-road heavy-duty vehicles. President Barack Obama in May had directed the two agencies to propose specific rules. NHTSA’s fuel-consumption standards and EPA’s carbon dioxide (CO2) emissions standards would be different for each of three regulatory categories of heavy-duty vehicles: combination tractors; heavy-duty pickup trucks and vans; and vocational vehicles, as well as gasoline and diesel heavy-duty engines. EPA’s proposed hydrofluorocarbon emissions standards would apply to air-conditioning systems in tractors, pickup trucks, and vans, and their proposed nitrous oxide (N2O) and methane (CH4) emissions standards would apply to all heavy-duty engines, pickup trucks, and vans. The emissions standards would begin with MY2014. EPA is also requesting comment on possible alternative CO2-equivalent approaches for MY2012-14 light-duty vehicles. NHTSA’s proposed fuel-consumption standards would be voluntary in MY2014 and 2015, becoming mandatory with MY2016 for most regulatory categories. Commercial trailers would not be regulated in this phase of the Heavy-Duty National Program, although there is a discussion of the possibility of future action for trailers. Comments are due by Jan. 31, 2011. The full proposal and instructions for comments are available at http://edocket.access.gpo.gov/2010/pdf/2010-28120.pdf.