“This is the one,” said Zenop Tuncer, leading the way to a corner of his car repair and restoration shop, where he had parked a rusty, aged hulk with running boards, an old-fashioned vacuum-tube radio and a history — though maybe not the history he thought.

The car is a 1942 Mercedes 320 Cabriolet D. Mr. Tuncer said it ran nicely when it arrived, but the body and the interior needed work, so he had called Mercedes-Benz to order parts. “As soon as I gave them the VIN number,” he said, using the abbreviation for vehicle identification number, “there were a lot of calls from Mercedes: ‘That’s Hitler’s car.’//” (The 10-digit number in question was actually the car’s factory number, or serial number.)

“In those years,” said Mr. Tuncer, whose shop is in Edgewater, N.J., “Mercedes was building cars for him and his staff. Mercedes was only for the top generals.” ...

But Adam Paige, a Mercedes spokesman, checked with an expert at the company’s archives in Stuttgart, Germany, who cast doubt on the Hitler connection, at least with this particular car...