Driving GM's new midsize models

Starting from the tony town of Del Mar, CA, through Torrey Pines state park and up the Los Penasquitos Canyon, then back down highways I-15 and I-5, Fleet Owner got the opportunity to put several versions of GM's new 2015 GMC Canyon and Chevrolet Colorado midsize pickups through their paces -- models equipped with the OEM's 3.6 liter V6 gasoline engine as well as its small block 2.5 liter I-4 gasoline-fired unit.