Enlarge By Kazuhiro Nogi, AFP/Getty Images Toshiyuki Shiga, of Japan's Nissan Motor, demonstrates charging the Nissan Leaf electric vehicle. Electric-vehicle provisions in federal fuel-economy and emission rules announced Thursday already threaten to shatter the uneasy truce among automakers, environmentalists and the Obama administration. The rules, proposed by the Obama administration in the fall, set a 35.5 mpg average for the U.S. auto industry by 2016. One of the only questions that remained about the final rules was how automakers would be credited for their electric vehicles in meeting emissions goals. Credits could be used by an automaker to offset emissions by its non-electric vehicles. In an apparent compromise, the Environmental Protection Agency capped at 200,000 per maker the number of electric vehicles that could be credited with a 0-gram rating for carbon dioxide (CO 2 ) through 2016. Additional EVs would be charged some responsibility for the CO 2 created while producing the electricity to charge them. Some environmentalists say the credits will reward automakers for building cars they would have built anyway. But the Union of Concerned Scientists' Jim Kliesch says at least regulators put a limit on the credits — to do otherwise would "significantly erode" the savings. "The issue is really: We want a true accounting of emissions," he says. "If substantial credit is given, it should not continue" forever. Gloria Bergquist, spokeswoman for the Alliance of Automobile Manufacturers, which favored no limit, says capping the credits impedes President Obama's goal of having a million electric cars on the road by 2015. Automakers also argue that emissions not created by operation of the vehicles shouldn't be their problem. "There is no precedent for holding companies responsible for the CO 2 generated by electric utilities. We do not determine what happens from the plug to the utility plant," Bergquist says. "It's unfair to base our compliance on what is entirely outside our control." The alliance, which represents all major automakers except Honda, notes the industry will sell 12 million vehicles this year and at least 60 million from 2012 through 2016. That makes the 200,000 cap unrealistically low, Bergquist says. Nissan alone plans to build 150,000 of its electric Leaf in 2012. But to ignore all of the emissions associated with EVs "would be poor public policy," Kliesch says. "These vehicles, despite their name, do produce emissions. They just don't do it at the tailpipe." Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more