Wilmington: General Motors Corp on Tuesday said it was closing four truck plants and could sell its Hummer brand to cut slow-selling trucks and SUVs from its lineup in response to higher gasoline prices the automaker now sees as a permanent threat to its business. CEO Rick Wagoner, speaking after a revised restructuring plan was approved by the automaker's board, said GM would close the four North American truck plants and add shifts at two US plants making more popular car models. In addition, Wagoner said GM was reviewing the Hummer brand and could sell the military-derived SUV line, which has become synonymous with gas-guzzling excess. "US economic and market conditions have become significantly more difficult,' Wagoner said, adding higher gasoline prices have caused consumers to swap out of highermargin trucks and SUVs faster than GM had expected. Wagoner added that GM's board approved funding for a next-generation compact to replace the Cobalt and a new subcompact to replace the Aveo. Both Chevrolet-branded small cars, which have been under development at GM's Korean unit, are set to go on sale in 2010. GM's board also allocated production funding to the Chevy Volt, a heavily touted, all-electric vehicle that GM expects to have in showrooms by 2010 and to assemble in Detroit. GM said the latest steps would cut $1 billion from its structural costs by 2010, but analysts questioned whether the steps would improve the automaker's turnaround prospects in the face of a US market now seen slumping well into 2009. GM shares, which have lost almost 60% since peaking in October last year, were up 3.7% at $18.10 on NYSE. Wagoner said GM, which has lost a combined $51 billion over the past three years, was not ready to detail a timeline for returning to profitability. Some analysts questioned whether the embattled automaker had moved too slowly, particularly with regard to Hummer. GM said it would stop making light trucks at plants in Oshawa, Ontario; Silao, Mexico, and two US plants. REUTERS ANOTHER ICONIC BRAND FINDS IT TOUGH Kick-start lOriginally built by AM General Corp in Indiana assembly plant lIn 1992, AM General began selling a civilian version of the M998 High Mobility Multipurpose Wheeled Vehicle to public under brand name