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Bruce Kopp/Eyewitness News

Plainfield, Aug. 25 - When it comes to used cars, you'll find the highest concentration packed on the property at 2950 E. Main Street in Plainfield near the airport.

"Typically, in 2004 we sell about 120,000 units in one way shape or form." Dave Emerson oversees the expanse of cars that flood into the operations of ADESA.

It's a publicly traded auto auction company celebrating its anniversary Thursday. Company officials rang the opening bell on Wall Street.

The auction is not open to the public. Only licensed dealers can bid on the cars there.

ADESA has become the nation's second largest used car auction with 52 locations around the country.

When a car lease expires or a rental car company sells off its fleet, the vehicles end up there. They'll only spend about two weeks on the property and at any one time ADESA can handle as many as 15,000 vehicles.

"We are the middleman," says Emerson. "The cars come from the manufacturers and their finance companies. The end user is the retail car dealership."

Area used car lots are flooded with inventory lately as new car buyers trade in the old set of wheels, taking advantage of the latest wave of employee pricing discounts.

But ADESA says that despite the ups and downs, its business doesn't feel the pinch from new car incentives. "We see them all and they have a ripple effect in our industry, and as long as they're selling new cars, they're selling used cars."

Driving the action is the behind the scenes body shop repair and detailing operations that rival any Detroit assembly line. About 300 cars are repaired and cleaned up each day. They're then auctioned off in an average time of 30 seconds.

More than two million cars roll through there each year. And as long as there are new car sales, ADESA says it sees no letup in the constant supply of used cars to auction.

General Motors Thursday announced it will extend its employee-pricing discount plan.