DELAFIELD, Wis. - The mechanics who work at Al Wagner's classic car business are putting in extra time this month, readying locally owned, vintage Lincolns for their roles in the Johnny Depp "Public Enemies" movie that is filming in Wisconsin.

Wagner, an engineer who formerly designed Corvettes for General Motors, owns An American Classic, a sales and restoration business he started in a historic garage building in downtown Delafield, Wis.

The shop specializes in classic Corvettes and other Chevrolets. But Wagner became involved with the movie production through one of his clients, a wealthy Milwaukee-area man who owns the seven-passenger black 1933 Lincoln that was once owned by gangster Frank Nitti.

The Nitti car and three others owned by the same man are being readied for scenes to be shot in Chicago over the next two months. The owner, who wants to remain anonymous, will drive the 1933 Lincoln in the movie.

The car, which had not been driven for 15 years, had been stored in Iowa. Only 110 of the 12-cylinder flat-head engine KB models were made, Wagner said. Because of its notorious owner, who was one of Al Capone's top henchmen, the car could be worth as much as $1 million, Wagner estimated. Without the Nitti connection, it might be worth half that, he said.

Such stratospheric values aren't common, but six-figure prices are not unusual in the world of classic car collectors.

And in a down economy, it's a good business to be in, Wagner said.

"They do very well in recessions," Wagner said. In bad times, some buyers view a classic car as a safer investment than the stock market, he said.

Wagner moved to Delafield in 1994, when he left General Motors to take a job at Harley-Davidson, where he worked in product development of Dyna motorcycles. After 10 years, he left Harley to turn his lifelong interest in classic autos into a business.

Wagner started with six cars that he owned, working from his home, which has a four-car garage. He bought a building that had housed an auto dealership and a fire station at various times in its 100-year history in 2005 and spent two years restoring it.

An American Classic is not open to the public. Wagner sees customers by appointment, to eliminate sightseers.

Most of Wagner's customers come from outside the area. Many of them stay at the Delafield Hotel, and their wives shop at the local boutiques while their husbands spend time looking under the hood.

He finds buyers through word-of-mouth connections in the collector community, and through ads in magazines aimed at collectors.

Brad Dovey, a stockbroker in Victoria, British Columbia, found An American Classic through an ad in Hemmings Motor News. Dovey, 42, flew to Wisconsin with his father and uncle and bought his dream car, a red 1972 Corvette LT1, from Wagner last fall.

He felt comfortable buying from Wagner because of his credentials. Dovey bought the Corvette because of his love for classic cars, not as an investment.

Of his Delafield experience, Dovey said: "It looked a lot like Mayberry to me."