“What kind of car is it?” one of the men inquired.  “What year is it?” asked the other.  They soon learned that the black car, parked in a prime spot in front of the Michelin-starred restaurant, was a 1955 Citroën Traction Avant. They responded with arched eyebrows and uncertain smiles before moving on.  Inside the busy restaurant, the car’s owner, Alain Daumas, sat with his wife, Magali, and the couple’s daughters, Léa, 5, and Julia, 2.  “It was a luxury car,” said Mr. Daumas, a jovial man with an outsize personality (think a French version of the actor Roberto Benigni). He wore an orange-stripe polo shirt and pale beige chinos.  When his job at a nonprofit education service brought about a move to Princeton, N.J., from Paris, last year, Mr. Daumas squeezed the Traction Avant (and a vintage trailer that he tows on longer trips) into a 40-foot shipping container with most of the family’s belongings.  “We had to leave some furniture behind,” Ms. Daumas said.  Mr. Daumas, 40, laughed broadly. “No bed, one car,” he said.  The Traction Avant — the name is French for front-wheel drive — has the look of an old-time mobster’s car. Made from 1934 to 1957, it was quite innovative by prewar standards. While it wasn’t the first car with front drive, it popularized the layout in Europe, and its unibody structure was considered advanced.  Like other Citroëns of the era, the styling of the Traction Avant changed little over its lifespan. The car has a long hood with generous fenders. The roof is high and the floor is low, affording more interior space than the car’s smallish size would suggest (perhaps a reason that Charles de Gaulle, listed at 6-foot-5, favored it).  Mr. Daumas acquired his Traction Avant from a business associate of his father’s, who had accumulated more vintage cars than he knew what to do with. The Citroën was in such dire shape when the man obtained it that it had cost him only a chainsaw.  The car’s condition did not improve under his care.  “Gosh, it was in ruins,” Mr. Daumas recalled. There was rust everywhere, and the engine had become a pantry for squirrels. But he was smitten.  He was living in Paris at the time and traveled to his father’s house in Le Mans to work on the car during the summer and on weekends. “He has a lot of space and a big garage,” Mr. Daumas said.  When he met Magali in 1997 and they fell in love, the project took on a little more urgency. The couple wanted to have the car for their wedding in 2000.  With an accelerated schedule, Mr. Daumas resorted to extreme measures. “I was coming back from Le Mans with one or two small pieces in my trunk to rebuild in the tiny basement of my house in Paris,” he said.  “Good memories,” he added. “Every screw has been disassembled and restored. In a Citroën, each bolt has the Citroën logo, and I wanted to keep that intact.”  Mr. Daumas used only original tools, as well as factory parts found with the help of friends and La Traction Universelle club, to restore the car. After five years and some 1,500 hours of work, he finished it with five days to spare.  “I broke it in at the wedding,” he said.  Mr. Daumas named the car Madeleine, after its original owner, whom he tracked down in the process of completing the paperwork for ownership.  He found the vintage trailer years later, through an online classified ad. He saw the ad late at night and arrived in the morning to make the purchase. After 500 hours of restoration work, the family put it to the test with a drive to Norway.  “We wanted to drive across the fjords,” Ms. Daumas said.  The Daumases have crossed the Scottish Highlands (a trip of 1,864 miles, Mr. Daumas estimated) and traced the path of the Tour de France. Now that they live in the United States, they plan to tour the country by car. At the top of the list? Times Square, which was where they were headed after lunch.  “I’ve always dreamed of driving down Broadway,” Mr. Daumas said.  Ms. Daumas buckled the girls into their car seats as her husband donned a pair of tan leather driving gloves.
When the Daumas family moved to New Jersey from Paris last year, they brought along their 1955 CitroÃ«n Traction Avant, a striking vehicle that looks like a mobsterâs car.