Detroit has vowed to change before, slimming down when sales slumped or pouring resources into vehicle quality to catch up to foreign competitors. Those efforts stalled or failed. But many auto analysts say the current makeover has a more permanent feel, largely because of the presence of the outsiders at the top and the lessons learned from the near-death experience of last year’s bankruptcies at G.M. and Chrysler.

Ford’s chief executive, Alan R. Mulally, broke the mold four years ago when he came from Boeing and set out to streamline Ford’s bureaucracy and integrate its worldwide operations. At G.M., Edward E. Whitacre Jr., a former AT&T chief, has replaced dozens of top officials with outsiders and younger executives, and driven the company to make decisions faster. Those efforts are likely to be accelerated under Daniel F. Akerson, who was named on Thursday to succeed Mr. Whitacre as chief executive in September.

And at Chrysler, Mr. Marchionne, an Italian raised in Canada who is both a lawyer and an accountant, is systematically upgrading the carmaker’s aged product lineup and revamping its plants in Fiat’s image.

“Fundamentally this thing has been reshaped, resized and rethought,” Mr. Marchionne said of Detroit. The biggest difference, he said, is that the Big Three have finally broken the habit of reflexively raising incentives to increase sales volumes.

“We’re not trying to kill each other for this month’s market share,” he said. “Those days are over. We’re not offering $7,000 checks to try to sell a car.”

Wave after wave of plant closings and worker buyouts in recent years has brought Detroit’s production more in line with the demand for its vehicles. Since 2000, the number of Big Three assembly plants in North America has dropped to 40, from 66, according to the consulting firm Oliver Wyman. In turn, overall capacity has shrunk to about eight million vehicles a year, from 13.7 million.

That still may be too much. After several years of sales topping 16 million vehicles, the industry nosedived to 10.4 million last year  the lowest since 1982. At current levels, sales are projected to edge up to about 12 million this year, with Detroit’s share running at 46 percent.