President Barack Obama's energy and climate assistant says the United States needs a unified federal standard for regulating greenhouse gas emissions from cars and trucks — and automakers, perhaps surprisingly, aren't that upset by the idea. That's the gist of a report from the Washington Post, detailing comments made Sunday by Carol Browner, who is head of a newly-created White House position to coordinate energy, environment and climate change policies across federal agencies. The idea is to form a unified policy that combines Environmental Protection Agency emissions regulations and the Department of Transportation's mileage standards, the Boston Globe reports. Browner laid out the plan at the Western Governors Association meeting in Washington, D.C. Part of the new regime would involve the cap-and-trade legislation that President Obama wants Congress to pass this year, according to the Post, which cited unnamed White House sources. Obama has said he wants a carbon cap-and-trade system to help reach a goal of cutting the nation's greenhouse gas emissions to 80 percent below 1990 levels by 2050, and the White House intends to release a budget this week that includes projected revenues from auctioning off emissions allowances under such a system, the Post reported. You might think that automakers would be upset at the idea of new federal regulations, but according to the Post, spokespeople from General Motors and the Alliance of Automobile Manufacturers trade group reacted positively to Browner's remarks, saying they would provide more certainty. Perhaps that's because they would rather see a federal standard in place than state-by-state regulations. California's plan to regulate vehicle greenhouse gas emissions was rejected by the Bush administration in 2007, but the EPA said earlier this month that it would reconsider that decision. That could open the door to an additional 13 states that want to set tail-pipe emissions limits stricter than current national standards (see Obama to Seek to Allow California, Other States, to Impose Emission Standards). Automakers also might be hoping a unified policy will ease President Obama's push to make cars 40 percent more fuel-efficient by 2020, with improvements set to start with 2011 models (see Obama: Cars Need to Improve Gas Mileage by 40%) Or perhaps it's because, with billions of federal bailout dollars in their pockets and their hands out for billions more, companies like GM and Chrysler aren't in a position to second-guess the government's efforts to push them to make their vehicles greener (see U.S. Automakers Get Federal Bailout).