The U.S. federal government on April 1 formally adopted rules that increase fuel-economy requirements for passenger cars and light trucks while for the first time imposing limits on greenhouse-gas emissions. The fuel-economy and greenhouse-gas limits are the same as ones outlined in a much publicized proposal delivered by President Barack Obama in the White House Rose Garden almost a year ago. The so-called National Program rules call for increasingly stringent fuel-economy standards beginning in MY2012 and reaching an estimated 34.1 mpg for the combined industry-wide fleet by MY2016. Because credits for air-conditioning improvements can be used to meet the U.S. EPA greenhouse-gas standards, but not the National Highway Traffic Safety Administration fuel-economy standards, the EPA requires that by MY2016 automakers achieve a combined average vehicle emissions level of 250 g of CO2/mi. The EPA standard would be equivalent to 35.5 mpg if all reductions came from fuel-economy improvements.