WASHINGTON – Auto makers, regulators and environmentalists open the annual Society of Automotive Engineers’ Government/Industry meeting here by treading heavily on what surely will become familiar battleground this year – whether new federal fuel-economy standards or state-level tailpipe emissions regulations proposed by California will control greenhouse gases and promote U.S. energy independence.

California’s emissions standard requires vehicles to achieve a fleet average of about 36 mpg (6.1 L/100 km) by 2016 and 43 mpg (5.4 L/100 km) by 2020. The new federal CAFE standard signed into law last year sets a national fuel-economy target of 35 mpg (6.7 L/100 km) by 2020, based on a fleet average for all light vehicles.

During the course of Monday’s day-long discussion, California’s effort to trim 60% to 80% of carbon-dioxide emissions from the transportation sector by 2050 finds an unlikely ally.

Keith Cole, director-legislative and regulatory affairs for General Motors Corp., says if reducing greenhouse-gas emissions is the goal, improving vehicle efficiency will do little to move the needle.

“The CAFE metric of a mile-per-gallon, or the efficiency of burning liquid fuels such as gasoline, is increasingly out of touch with the technologies you would choose if you selected the carbon-centric approach of looking at what is the best way to reduce tons of CO2 emitted,” he says. “The environment does not care about miles per gallon of gasoline consumption. It cares about tons of CO2.”

Cole goes so far as to express a desire to see an auto industry regulated by California emissions standards.

“Just use tons of carbon to regulate and let us get there,” he says. As a means to hitting the 80% reduction, he cites second-generation, cellulosic biofuels in flex-fuel vehicles; extended-range electric vehicles, such as the Chevrolet Volt, charged by a clean electric grid; and fuel-cell vehicles running on hydrogen.

“These technologies are all directionally correct,” he says, noting GM is working on all three areas and also revealing the auto maker’s support for the framework of a cap-and-trade proposal included in a climate-change bill from Sens. Joe Lieberman (ID-CT) and John Warner (R-VA).

Cap-and-trade legislation would provide a way to reduce greenhouse gases on an industrial scale by capping total annual emissions and letting the market assign a monetary value to any shortfall through trading. Credits can be exchanged between businesses or bought and sold in international markets at the prevailing market price.

Cole also reiterates GM’s position that separate state emissions standards, a regulation adopted by the California Air Resources Board (CARB) in 2005 called AB 1493, along with CAFE, will not trim greenhouse-gas emissions. Rather, he insists the two standards would combine to push greenhouse-gas emissions higher.

California is fighting a decision from the Environmental Protection Agency that last year struck down the state’s authority to regulate tailpipe emissions under regulation AB 1493.

Cole says an “economically rational” auto maker would put the necessary technology on vehicles sold in the 12 states that have adopted California’s emissions laws, while offsetting those costs with less technology in the 38 states not under such strict laws.

“If (auto makers are) perfectly adept at doing that, the impact of (AB 1493) is precisely zero,” Cole says.

John German, manager-environmental and energy analysis, American Honda Motor Co. Inc., agrees with Cole. He says Honda can build vehicles to meet separate state standards, but that would delay big gains in reducing greenhouse-gas emissions.

“If you offer different vehicles in California, that means we take our experienced engineers and redirect their efforts,” he says. “In the long run, it’s probably going to slow us down from getting to a long-term solution.”

Roland Hwang, director-vehicles policy for the Natural Resources Defense Council, says a cap-and-trade policy combined with incentives for auto makers to build more fuel- efficient vehicles, plus sound regulation, could trim CO2 emissions 18% to 30% by 2020 and 80% by 2050.

However, he notes that by 2020, the California standard would push fuel economy to 40.8 mpg (5.8 L/100 km), vs. 35 mpg for CAFE. “I don’t like the mpg comparison, but for those who can’t get out of that world, California (regulations) would be better,” Hwang says.

Hwang also credits California with playing a key role in pushing a higher CAFE standard into law. Without the state’s higher fuel-economy proposal, he says politicians may not have set as high a federal standard.

But Thomas Darlington, president-Air Improvement Resources Inc., calls California’s standard flawed because it has not gone through feasibility studies or cost analysis. Ultimately, CAFE will provide a greater reduction in emissions and higher fuel economy.

“(California’s emissions targets) haven’t been adopted by CARB or EPA,” Darlington says. “So in a way, they are just a bunch of numbers hanging out there that need to go through the standard rulemaking process.”