DETROIT – After losing American market share in 2004, General Motors Corporation will trim its workforce this year, the chairman and chief executive, Rick Wagoner, told reporters at the North American International Auto Show here yesterday.

But there won’t be any formal American job cuts at the world’s largest auto maker, he said.

GM expects a 5% reduction in hourly workers and a 2% drop in management ranks through retirement and other normal attrition, Mr. Wagoner said.

GM will continue its long-term strategy for cost-cutting, the executive said.

“In 2005, it will be more or less business as usual,” he said.

Mr. Wagoner said he expects North American industry production of about 17.3 million vehicles in 2005, about flat with last year.

GM will continue to chip away at its high health-care costs, Wagoner said, but he doesn’t see any easy solutions.

Asked about GM’s restructuring plans in Europe, where costs must come down quickly, Mr. Wagoner said he couldn’t comment on charges the company will take.

He said the company may address that question during its fourth-quarter earnings conference call next week.

It is possible for GM to increase its American market share this year, Mr. Wagoner said.

“The opportunities are clear. We have 20% to 25% new products this year, compared with 10% to 12% new products in 2004,” he said.

Mr. Wagoner said he doesn’t see GM’s full-sized pickup business growing this year, as the company doesn’t have its new model ready.