At G.M., about 35,000 workers will leave at the end of the year, the company said.

The number, representing nearly a third of G.M.'s 113,000 hourly workers, is significantly higher than the company had expected. As a result G.M., which intends to close 12 plants by 2008 to pare costs and become more competitive, will reach its goal of eliminating 30,000 jobs two years ahead of schedule, the chief executive, Rick Wagoner, said.

''This was a difficult but necessary move,'' Mr. Wagoner said at a news conference at G.M.'s headquarters in Renaissance Center here.

At Delphi, G.M.'s largest auto parts supplier, more than half of its 24,000 workers, or 12,600, accepted similar early retirement packages. The number was also greater than expected and should help Delphi emerge from bankruptcy protection as a more efficient company.

Analysts said the large number of departures suggests that many workers believe that staying on the job would be as much of a gamble as quitting. In his remarks, Mr. Wagoner assured employees staying that the company is making progress in its turnaround efforts and that the times ahead would be better.

In recent years, G.M. has surrendered a significant amount of market share to foreign automakers and had the capacity to produce far more cars than it could sell. The buyouts and early retirement packages represent a big step toward making the company, still the world's largest automaker, profitable again.

''This is a big, big hunk of ballast over the side,'' said James P. Womack, chairman of the Lean Enterprise Institute in Cambridge, Mass.

The announcement of the numbers was made at 5:15 p.m., after the markets closed. Earlier, shares of G.M. rose 78 cents, to $27.75.

Specifically, about 30,400 G.M. workers, who had at least 26 years on the job, took early retirement packages that include payouts of up to $35,000 and full benefits. The remaining 4,600 will receive either $70,000 or $140,000, depending on their experience, but give up all their benefits except their pensions.

Employees at both G.M. and Delphi who accept the deals have seven days to change their minds. Mr. Wagoner said that window had closed for nearly all of those who said they planned to leave and that he did not expect the final number to change significantly.

The program will cost G.M. about $3.8 billion but save it $8 billion a year, $1 billion more than Mr. Wagoner had previously said. G.M. lost $10.6 billion last year.

Workers had to weigh not only G.M.'s prospects but also what continued employment would mean. The contract of the United Automobile Workers with all the Detroit automakers expires next year, and the union president, Ron Gettelfinger, recently said that the union might be forced to make some concessions in the new contract.

''There's always the possibility that if they don't take the buyout, the situation down the road could be worse,'' said Gary N. Chaison, a labor relations expert at Clark University in Worcester, Mass.

For many of the workers who will leave, G.M. is the only employer they have ever known. They were hired at a time when the auto industry promised high wages and a secure future.

Some not yet ready to retire will use their payouts to begin new careers. Richard Luedtke, a certified financial planner who conducted workshops about the buyout offers for G.M. workers in Toledo, Ohio, described those who attended as scared and overwhelmed by the offers.

''Most people never expected they'd have to make a decision about retirement so soon,'' Mr. Luedtke said. ''Some people wanted to go do something else, even if it only means $10 an hour.''

G.M.'s plant in Oklahoma City had the largest number of workers opting for a buyout, though the plant was already closed and the workers were in a jobs bank, a contractually mandated program that gives them most of their pay when on layoff. The company said 1,533 workers out of 2,360 at the plant took the packages.

At G.M.'s assembly plant in Arlington, Tex., 799 of the 2,700 U.A.W. members who build the Tahoe, Yukon and Escalade sport utility vehicles filed for the deals. That is about 200 more than J. B. Brown, the local president, had expected.

''They're excited about the chance to do something else,'' he said.

Many of the thousands of G.M. workers in the jobs bank will be called back to replace departing workers, although there are not expected to be enough open positions for everyone.

Although more workers will leave than G.M. anticipated, Mr. Wagoner said plant closings will not be accelerated. Temporary workers will be used to fill voids until permanent employees can be shifted to locations where there is a demand.

G.M.'s annual earnings will increase about $1.25 a share for every 10,000 workers who leave, John Murphy, the automotive analyst at Merrill Lynch, wrote in a recent report. (G.M. lost $9.55 a share last year.) But Mr. Murphy noted that the cost of hiring temporary workers would noticeably offset those savings if significantly more than 30,000 workers departed.

Photo: Rick Wagoner, G.M.'s chief executive, said yesterday that the buyouts were ''a difficult but necessary move.'' (Photo by Bill Pugliano/Getty Images)(pg. C6)