This season's most-powerful light-truck engine is General Motors' 2006 Duramax LBZ diesel available in the Chevy Silverado/GMC Sierra 2500 and 3500 Series pickups. The V8 diesel delivers 360 horsepower at 3,200 rpm and 650 lbs.-ft. of torque at 1,600 rpm (the strongest competitors from Ford and Dodge currently are rated at 325 hp/570 lbs.-ft. and 325 hp/610 lbs.-ft., respectively). Duramax's fuel economy improved even as power increased. One transmission choice available on GM trucks with the big diesel is the Allison 1000 6-speed automatic. Estimated list price: (Duramax option) $5,310.