The Associated Press

DETROIT - General Motors Corp. says it is trimming production of its slow-selling Ion compact car at its Saturn assembly plant in Spring Hill, Tenn., affecting 300 to 400 jobs, though union officials say no one will be laid off.

The automaker told employees this week it will reduce the number of work crews in the plant from three to two, effective Sept. 7. The plant now operates with three crews of 300 to 400 workers over two shifts, six days a week.

How many jobs will be eliminated, if any, was uncertain Thursday.

GM said it will offer some idled workers a special separation package that has not been determined. Other employees will be reassigned.

United Auto Workers Local 1853 chairman Mike Herron said Thursday that workers from the dissolved shift will fill vacant positions and vacation-replacement shifts as well as take on assignments related to upcoming construction at the factory.

"There's no plan to have any of those people leave the plant," Herron said.

GM's board decided Aug. 3 to spend $400 million to $500 million to upgrade the Spring Hill plant to produce the next generation of the Ion and Saturn Vue sport utility vehicle.

The factory employs 5,600 workers, including those who build the Vue. Production of the Vue is not affected.

"We're removing a shift of production to better align the plant's output of the Ion with market demand," Saturn spokeswoman Sherrie Childers-Arb said.

Sales of the Ion, introduced last year and priced starting at $10,995, are down nearly 11 percent so far this year compared with the first seven months of 2003. Lagging demand has forced Saturn to idle the Ion production line for 13 weeks over the past 10 months.

GM shares closed down 92 cents at $40.82 on the New York Stock Exchange.