'This is in direct response to decreasing market demand, which is hitting across the industry,' Sapienza said. At the Pontiac Assembly plant, which produces the Chevrolet Silverado and GMC Sierra, 700 of the plant's 1,200 hourly workers will be laid off as GM reduces plant output from 55 trucks per hour to 24 trucks per hour. The cuts will take effect Feb. 2, Sapienza said. At Detroit-Hamtramck -- the plant that builds the Buick Lucerne and Cadillac DTS -- production will slow to 38 vehicles per hour from 56. Production has fallen sharply at the plant this year, down 34 percent. GM will lay off about 500 workers effective Jan. 12, Sapienza said. The company notified the state of Michigan about the cuts last week. Earlier, the company had said 400 workers would be laid oof at its Detroit-Hamtramck plant. A UAW official at Local 22 said the precise number of people laid off wouldn't be known until January. In Wilmington, Del., the plant that builds the Pontiac Solstice, Saturn Sky and Opel Roadster, the work force will be reduced from two shifts to one on Dec. 8, affecting 400 hourly jobs, he said. The plant built just 1,350 vehicles last month, down from 2,959 in September 2007. Production has fallen 49.5 percent through the first nine months. Earlier this week, GM announced a series of measures to speed up production cuts, including closing its Janesville, Wis., and Moraine, Ohio, assembly plants on Dec. 23 -- ahead of schedule. The company had previously said it would close the two plants by 2010. GM also announced it would close its Grand Rapids stamping plant by the end of 2009. The Wyoming, Mich., plant employs 1,500 people. GM's U.S. sales are off 18 percent through September, to 2.4 million vehicles, down from 2.9 million vehicles over the same period in 2007. The U.S. auto industry had its worst month in September -- selling less than 1 million vehicles in a month for the first time since 1993. Auto sales are off 13 percent this year industrywide, and some analysts predict that October could be the worst auto sales month since 1983, on tougher lending standards and mounting concerns about the economy. GM is cutting costs by $10 billion by the end of 2009 as part of a plan to boost liquidity by $15 billion. The automaker lost $19 billion in the first six months of the year and is expected to report a significant third quarter loss in the coming weeks. You can reach David Shepardson at (202) 662 - 8735 or dshepardsondteom.