Buick, Pontiac and GMC dealers will get 12 new or special-edition vehicles over the next 20 months — but they won’t get a Pontiac Trans Am.

Pontiac had lobbied for a sibling vehicle to the Chevrolet Camaro, which is scheduled to arrive in February 2009.

General Motors’ plan to make Pontiac a rear-wheel-drive performance car division is likely to be scaled back because of fuel economy regulations, GM leaders told dealers at the make meeting.

One dealer said the business case for the Trans Am didn’t compute.

“It was an economic situation,” said Lynn Thompson, owner of Thompson Motor Sales in Springfield, Mo. “It would cost $200 million to bring out the vehicle.”

Pontiac will remain a car-only brand for the foreseeable future, dealers were told. But because of new legislation requiring vehicles to reach a fleet average of 35 mpg by 2020, Pontiac might not end up as GM’s performance division, dealers said they were told.

“The plan is being tweaked because of the gas situation,” Thompson said. “I hope they don’t give up on performance because they don’t have to. You can use four-cylinder engines to achieve incredible power.”

B-P-G will give dealers six new or special-edition vehicles — such as the special-edition GMC Sierra pickup, called Pro Grade — this year. They will get another six next year, dealers who attended the meeting told Automotive News.