2017 GMC Sierra 2500HD Diesel 4×4 Crew Cab

View photosWhat’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