Automakers facing new U.S. fuel-economy rules in 2012 have questions about getting credits for fuel-efficient technologies and being penalized for not complying with the law, but they will ultimately support the proposed national standards, officials from an industry group say.

The Alliance of Automobile Manufacturers, a lobbying group of 11 automakers, has until late next month to decide which parts of the government’s proposed emissions rules are fodder for official comment, spokesman Charles Territo said  in an interview with Automotive News reporters and editors.

The Alliance and individual automakers plan to weigh in, but they don’t want to get in the way of getting  the Coporate Average Fuel Efficiency (CAFE)  standard officially passed by the beginning of April.

In remarks prepared a Wednesday public hearing in Detroit about the emissions rules, Julie Becker, the alliance’s vice president for environmental affairs, said all parties involved must start moving forward toward passing the legislation.

“A final rulemaking prior to April 2010 is essential to providing manufacturers with the certainty and lead time necessary to plan for the future and to cost-effectively add new technology,” Becker said.

The Alliance is considering giving opinions on how the government should give automakers credits toward their fuel-efficiency scores for using emissions-reducing technology such as improved air conditioning units, Territo said.

In addition, the Alliance may issue comments on how the government should penalize automakers who don’t meet emissions standards or how regulators should account for diesel emissions in an automaker’s companywide average, he said.

In May, President  Obama said the United States would implement a single national emissions standard, harmonized between the EPA’s greenhouse-gas regulations and the National Highway Traffic Safety Administration’s (NHSTA)  fuel-economy parameters.

The proposed standard calls for the vehicles sold in the United States to average 35.5 mpg, although individual manufacturers’ fleet averages would vary. All manufacturers would have to hit targets for emissions based on each vehicle’s wheelbase. The result would be a 40% improvement in fuel economy from current levels.

The proposed rules on how to meet the new standard came out in September. Automakers have until Nov. 27 to submit written comment on the potential regulation.

In the meantime, the government has scheduled three public hearings this month in Detroit, New York City and Los Angeles to allow citizens to voice their opinions on the legislation. The first is today.

Despite plans to weigh in, “at the end of the day, we will support this program,” Territo said. “If it isn’t finalized, we would revert to the California program, and that is the worst-case scenario.”

The proposed rule supersedes a waiver California has received to develop its own fuel-economy standards.

The Alliance also plans to stress to regulators the importance of moving on to develop a national standard for 2017 to 2020, Territo said.

“The more time you have to develop new technologies, the less expensive it is,” he said.

The Alliance’s members are BMW Group, Chrysler Group, Ford Motor Co., General Motors Co., Jaguar Land Rover, Mazda, Mercedes-Benz USA, Mitsubishi Motors, Porsche, Toyota Motor Corp. and Volkswagen Group.