We traveled to GM’s Proving Grounds outside of Phoenix, AZ to drive the new GMC Sierra and Chevrolet Silverado pickups and were treated to an exhaustive display of the new truck’s capabilities. Over the span of two days and about 250 miles we were able to drive virtually every main configuration under load and off, drive 2006 model-year competitors back-to-back on an autocross course, and take part in a revealing, maximum capacity towing exercise. General Motors officials opened doors and allowed complete scrutiny during the trip.