CHICAGO – The ’13 Chevrolet Corvette "is the finale for the C6 generation," says Harlan Charles, Chevrolet’s Corvette product marketing manager.

He declines to offer details about the coming next-generation C7, other than to warn those still hoping to purchase a C6 model to act fast, especially when it comes to the 638-hp ZR1 rocket.

"The current ZR1 may be the high-water mark for Corvette for awhile," Charles says in an interview at the auto show here, suggesting that the debut of the C7 won't include a potent ZR1 rendition at the outset.

"It may be awhile before another ZR1 in the future, so if you want one, get one now," he says.

And lest anyone think otherwise, “with the ZR1, there are no backlogs.”

In other General Motors show news, GMC earlier at the show unveiled refreshed versions of the Acadia and Acadia Denali cross/utility vehicles that will go on sale later this year as ’13 models, but their Chevy Traverse and Buick Enclave platform mates were missing.

Both Tony DiSalle, vice president-marketing for GMC/Buick, and Bruce Mader, product manager-CUVs for GM, decline to talk about plans for the Traverse or Enclave.

However, sources say while the Acadia was given a spotlight at the show, the other CUVs will receive the same re-dos at the same time, given the obvious fact all are built in the same plant.

The two GM executives also will not comment on the future of the Granite, the small GMC CUV concept unveiled on the auto show circuit two years ago.

The concept, which is smaller than the Scion xB and powered by a 1.4L turbo 4-cyl engine, still hasn't been approved for production, or if it has, no one issaying.

Rumors call for a 2013 or 2014 debut, but mum’s the word at the auto maker. "Can't talk about it," says DiSalle. Ditto for Mader.