Three US big automakers -- General Motors, Ford, Chrysler -- all posted double-digit sales increases year on year last month, according to statistics released Friday. General Motors Co. said its October U.S. sales rose 15.7 percent to 226,402, led by growing sales of its Malibu midsize cars, Impala full-size cars, Silverado and Sierra pickups. Sales of Ford Motor Co. surged 14 percent last month to 191,985, the company's best retailing performance for the month of October since 2004. Meanwhile, Chrysler Group LLC said its sales rose 11 percent to 140,083 in October, also the automaker's best retail sales for October since 2007. The auto sales for both the Ford and Chrysler, however, narrowly missed analysts' expectations for the month. Sales of Chrysler's Ram pickups rose 18 percent to hit nearly 30,000 and 5, 120 Dodge Durango SUVs were also sold in the past month, up 59 percent. Market analysts say auto sales were mostly unaffected by the 16- day partial federal government shutdown in October but there may be minimal future sales impact for those Americans who delayed purchases because of the shutdown.