Report: Obama will drive up miles-per-gallon requirements

— -- The Obama administration is set to announce Tuesday what will amount to a sweeping revision of auto-emission and fuel-economy standards in the same package.

By limiting the amount of carbon dixoide cars can emit, it will have the effect of requiring automakers to boost overall fuel economy to 35.5 miles per gallon by 2016, notching up 5% each year from 2012, according to a person familiar with the details but not authorized to speak on the record before the official announcement Tuesday.

That's a steeper improvement than required in the 2007 Energy Act, which mandated 35 mpg by 2020. But it's more lenient than a regulation pending in California that would require about 40 mpg by 2015.

Previous rules have addressed only fuel economy. California has a pending standard for carbon emissions, but it's been stymied by automakers' lawsuits.

California, 13 other states and the District of Columbia have urged the federal government to let them enact more stringent standards than the federal government requires.

The Obama rule would be first to combine emissions and fuel economy, and makes it perhaps the most dramatic auto regulation since the Clean Air Act of 1970. That landmark act set auto pollution standards for the first time, and required that lead, a poison, be removed from gasoline.

Roland Hwang, who oversees transportation policy for the Natural Resources Defense Council and has been part of the discussions with the White House and California officials, says the new standard should reduce emissions of so-called greenhouse gas 30% by 2016.

Greenhouse gases, chiefly carbon dioxide, are blamed for global warming. Autos emit less than 20% of all human-made greenhouse gases, the government says.

While details remain to be worked out, the new standards are expected to:

• Give car companies the single nationwide standard they want, avoiding what they have opposed as a patchwork of state clean-air regulations that could force them to offer different models in different markets. That would be a costly complexity for an inudstry on the ropes.