General Motors Corp. is constructing the largest auto show exhibit ever built in North America.

The colossal 164,456-sq.-ft., two-level showcase is under construction for the North American International Auto Show, a January event spon-sored by the Detroit Auto Dealers Association.

The exhibit will be called "The GM Experience." It will house all the automaker's brands, including Saab and Saturn, plus vehicles from overseas subsidiaries such as Vauxhall and Opel.

The image-conscious project is designed to drive home a message that GM is on the leading edge of design and innovation.

"We want to make that statement, and the Detroit auto show is an ideal environment to tell the story of the new GM," says GM North America President Ronald L. Zarrella.

He's coy about how much it will all cost. "More than $10 million and less than $100 million," says Mr. Zarrella, leaving much to the imag-ination.

GM reportedly felt upstaged by Ford at the show last year. The two-decker Ford exhibit covered 94,000 sq.-ft. It drew huge crowds.

But Mr. Zarrella says plans for the upcoming extravaganza were on the drawing board well before Ford showed its stuff at the 1999 show.

"Our new exhibit is not a question of outdoing Ford," says Mr. Zarrella. "When I first saw the Detroit auto show, I thought, 'We're the biggest automaker in the world and we're scattered about.'

"Chrysler had a much stronger presence because their products were all contiguous. The new exhibit is a question of what's the appropriate presence for the world's largest automaker."

It will require 230 tons of steel which, if melted into I-beams and placed end-to-end, would be three times taller than Mt. Fuji and 105 times longer than a pro soccer field.

Exhibit highlights will include a 1,200-seat amphitheater, a Hard Rock-like cafe and a VIP area for 300 guests.

Vehicle displays will include four concept cars (including the Buick LaCrosse and GMC Terradyne), two new pro-duction vehicles and antiques reflecting GM's heritage.

Nearly 300 GM employees and temporary contract workers will staff the place. Among product specialists, on the floor to answer questions about vehicles, will be 164 UAW members. That's considered a sign of GM's mellower relationship with the auto union.