Owner Michael Sewell was really impressed by the performance of the new engine. All three owners we interviewed drive Sierras with the 355-hp, 5.3-liter V-8, but the truck is also offered with a 4.3-liter V-6 that puts out 285 hp and, later this year, a 6.2-liter V-8 said to put out an estimated 420 hp and 460 lb-ft. All three engines are backed by six-speed automatics. The engine family is called EcoTec3, because of the three key technologies: direct injection, continuously variable valve timing, and Active Fuel Management. These features make the new engines vastly more efficient than before.
Active Fuel Management is standard in the V-6 and in both V-8s. In all three cases, AFM shuts off cylinders (two in the V-6, four in the V-8) to make the best use of the engine, without the driver being able to hear or feel the difference. The owners were all impressed with the new engine technology, because of the combination of more power and better fuel economy. All three engines put out a lot more power than the previous engines did (up to 40 more horsepower and up to 57 lb-ft more torque) and provide increased towing and payload capacity. In addition, the 5.3-liter provides best-in-class V8 fuel economy.