2012 GMC Sierra All Terrain HD Concept video at the 2011 Detroit auto show

Detroit, Michigan, USA April 24, 2013, 10:35 a.m. GM's super-size - Obviously based on GM’s full-size HD platform, the Concept uses a modified version of the pickup’s 4WD system, the new 6.6-litre Duramax Diesel that produces 397 horsepower and 765 pound-feet of torque and the Allison 1000 six-speed automatic transmission. Auto123.TV 2011  Videographer: Auto123.TV | © Auto123.tv