What?s 220 pounds to General Motors? new 6.6-liter Duramax diesel V-8 engine" Not much, based on the minuscule differences between the performances of the 2017 GMC Sierra 2500HD tested here and a slightly smaller, extended-cab Chevrolet Silverado 2500HD with the same engine we tested earlier this year. This 8000-pound GMC?a high-zoot, crew-cab Denali model?is 9.5 inches longer and 220 pounds heavier than that Silverado, yet it trails the Chevy to 60 mph by only 0.3 second and by 0.2 second through the quarter-mile. This ?slower? four-ton truck?s performance figures are remarkable: 6.5 seconds to 60 mph and a quarter-mile time of 15 flat at 91 mph. READ MORE ??
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