When General Motors Corp. pulls the cover off a new supercharged version of the Corvette at the Detroit auto show next month, it will unveil a performance car designed to rival or better even the fastest, most expensive exotic cars from Europe.

But the Corvette's chief engineer says the 2009 Corvette ZR1 may be the last in a long tradition of Detroit performance cars, endangered by stronger federal fuel economy regulations and limits on carbon dioxide emissions.

"High-performance vehicles such as this may actually be legislated out of existence," Tadge Juechter said at a recent showing of the ZR1, which is designed to have around 620 horsepower.

President Bush on Wednesday signed into law legislation that will bring more fuel-efficient vehicles into auto showrooms and require wider use of ethanol, calling it "a major step" toward energy independence and easing global warming.

The legislation requires automakers to increase fuel efficiency by 40 percent to an industry average 35 miles per gallon by 2020.

But Juechter said to sell one of the Chevrolet supercars, GM would need to offset that with cars that get 45 mpg.

"It could really be an endangered species," he said.

Aaron Bragman, an auto analyst with the consulting firm Global Insight, said predicting the death of the muscle car might be premature.

The Corvette, he said, is fuel efficient when compared with its competitors. Although fuel economy figures weren't released for the ZR1, the current 505-horsepower Corvette ZO6 gets an estimated 15 mpg in the city and 24 on the highway, according to GM.

The ZR1, he said, gets around the same mileage as a Chevrolet pickup truck, and GM won't be getting out of the pickup business because of gas mileage standards.

"I think it's a little over-dramatization," Bragman said. "GM wants to sell big, high-performance, fun cars. And typically that's what Americans want to buy."

Performance cars of the future may be powered by smaller engines or electric motors, he said, but they won't die.

The ZR1 will have a top speed of more than 200 mph, driven by an all-new supercharged 6.2-liter V-8 engine. It has 19-inch front and 20-inch rear wheels and a suspension tuned to provide extraordinary cornering grip, GM said.

The car has a carbon-fiber hood, fenders and roof for weight savings, and its huge carbon-ceramic brake rotors give it great stopping power, the company said.

The ZR1 will cost around $100,000 and probably will go on sale next summer.