Since the current-generation GMC Sierra 1500 pickup debuted four years ago, competing trucks have outpaced the GMC with recent redesigns. But don’t assume the Sierra (or its Chevrolet Silverado twin) is ready to be put out to pasture just yet. Over its production run, this full-size truck has seen its share of improvements on top of the solid foundation on which it started. Despite the mounting pressure from rival manufacturers, the 2011 Sierra 1500 remains one of the best trucks in this category.