http://VacavilleGMC.com 866-593-1568 The standard power plant for the 2013 GMC Sierra 3500HD is a 6.0-liter gasoline V8 engine that produces 360 horsepower and 380 pound-feet of torque. A six-speed automatic is the only available transmission. An optional 6.6-liter turbodiesel V8 is the engine of choice for those who plan on towing or hauling on a regular basis. It produces 397 hp and 765 lb-ft of torque and is mated to a beefier six-speed automatic transmission with manual shift control. In performance testing, a 3500 Denali with the turbodiesel engine and standard rear axle went from zero to 60 mph in 7.5 seconds, about a second quicker than the diesel-powered Ford F-350.