Lutz: RWD Chevy Impala, Pontiac GTO shelved

General Motors would like to offer a new Chevrolet Impala and Pontiac GTO based on its new Zeta rear-wheel-drive platform, but the much-rumored programs are "gone for now," GM Vice Chairman Bob Lutz has said. "We've got nothing in the product plan right now like that."

Lutz said building more midsize to large Zeta vehicles is not a good strategy with America's new CAFE fuel economy standards in mind. While the new Chevy Camaro and Pontiac G8 use the platform, don't expect to see other GMs with the same underpinnings in the near future.

Lutz told the publication he halted or killed off several Zeta programs as a direct result of the CAFE regulation being approved by the U.S. government.

Such vehicles are not at the end of the market where GM wants to "stimulate demand," Lutz told Australia's GoAuto. Rather, GM is hoping to boost sales of smaller, more efficient vehicles. Under the new CAFE law, automakers must have a fleet average of 35 mpg by 2020.

Even emphasizing V6 and hybrid powertrains over the V8 offerings won't be enough to hit the 35 mpg goal with more vehicles like the G8 and Camaro, he said.

Smaller "Alpha" cars still on the table

Zeta might be mostly dead, but GM is still moving ahead with development of vehicles built on its Alpha rear-drive architecture, Lutz said. The new Cadillac BLS and Pontiac G6.

Lutz cautioned development of the Alpha vehicles might be delayed while "we sort our way through this 35 mpg task." He said a small rear-wheel-drive car is about 1 mpg less efficient than a similar front-wheel-drive vehicle.