The decision to announce the number of arson attacks was itself controversial. Mr. Valls said he was speaking in the name of “the truth due to the French people,” a reference to the decision by former President Nicolas Sarkozy’s government three years ago to suppress the data in the hope that it would keep juvenile delinquents in French towns from trying to outdo one another.

During the autumn 2005 riots that rocked some of Paris’s more volatile suburbs, more than 8,800 cars were burned. At the time, French television censored images of the car-burning so as not to encourage the practice.

One area that figured in those riots, the department of Seine-Saint-Denis that encompasses parts of Charles de Gaulle Airport, led all regions in cars burned on New Year’s Eve, with 83.

Bruno Beschizza, a member of Mr. Sarkozy’s U.M.P. party with responsibility for security issues, derided the decision to publicize the data, saying Wednesday in a statement that Mr. Valls “had taken the risk of reigniting the competitions between areas and between rival gangs to see who can burn the most vehicles.”

Not all of the cases are simple arson attacks. Some are joy riders or car thieves covering their tracks. Mr. Pénet said unscrupulous car owners have taken advantage of the phenomenon to cash in on their insurance policies.

“We estimate that less than 20 percent of the vehicles are burned for insurance fraud,” he said, “but it is significant.”

He said about 85 percent of cars carry fire insurance, with an average payout of €5,000 per burned car. With 40,000 cars burned annually in France, that works out to about €170 million per year. While that is a lot of money, Mr. Pénet said, it is but a small part of the €60 billion in payouts French auto insurers make each year. And while it means everyone pays higher premiums, it does not add much to car insurance in absolute terms, he said.

“It’s very visible in terms of delinquency, as a societal phenomenon,” he said. But from the point of view of the insurers, “it’s not that important in the grand scheme.”