President Barack Obama is expected to announce today a new federal mandate that will require automakers to improve car and light truck fuel mileage in an effort to reduce carbon emissions by 30 percent by 2016.

It is the first time the federal government has imposed limits on the emission of greenhouse gases from cars and trucks, The New York Times reported. It also sets a single federal standard, settling a request from California to impose its own tougher vehicle emission standards, which the Bush administration opposed and the Obama administration was considering. Thirteen other states and the District of Colombia also said have said they planned to adopt California’s program.

The plan will gradually be phased in, starting in 2012. Under the proposal, cars would be expected to raise their current 27.5 miles per gallon standard to 39 mpg by 2016, while the light truck average would rise to 30 mpg from 24, the Associated Press reported.

Automakers are expected to support the plan because it sets a single national efficiency standard, a reasonable timetable to meet the mandate and a certainty in regulations that allows manufacturers to move forward with product development plans.