The automaker's US sales fell 12% in the first four months of this year, faster than the 7.7% industry slide. US industry sales may not have reached their lowest point for the year yet, GM chief sales analyst Mike DiGiovanni said on a conference call yesterday. Rebound Anticipated GM said it expects a sales recovery in the second half as consumers spend tax-rebate checks from the government's economic stimulus package. GM's costs are mounting. In a May 8 filing, GM disclosed the contribution to end the American Axle strike, which has idled all or part of as many as 33 GM factories. The United Auto Workers walkout at American Axle cut the automaker's output by 230,000 vehicles through April and cost $US800 million in the first quarter, GM has said. The strike reduced GM's cash flow by $US2.1 billion in the first quarter because automakers get revenue when a vehicle is built, rather than when it's sold.