2012 Gmc sierra 2500hd fuel economy Read Also: 2007 Gmc sierra 2500hd fuel economy 2004 Gmc sierra 2500hd fuel economy 2008 Gmc sierra 2500hd fuel economy 2012 Gmc sierra 2500hd diesel fuel economy 2009 Gmc sierra 2500hd fuel economy 2012 Gmc sierra 5.3 l fuel economy