Combining a 6.0-liter V8 engine, two electric motors and a "gearless" variable transmission, the Sierra
Hybrid promises fuel economy improvements of 40 percent in city driving and 25 percent overall compared with gas-only models (which top out at 15 city/20 highway mpg). It can move on electric power alone at speeds up to 30 mph -- even while towing -- and shut down four of its eight cylinders while cruising. The Crew Cab-only
pickup will be available with two- or four-wheel drive and feature max payload and towing capacities of 1,459 and 6,100 pounds, respectively. Look for it Fall 2008 at prices to be announced.