GM's diesel off-roaders ready to wander It's a pickup truck nerd's dream come true. Although it didn't go out of its way to advertise them, General Motors left a couple of 4x4 surprises at the Detroit Auto Show. We've already been told that the 2015 GMC Canyon and Chevrolet Colorado midsize pickups will be available with special off road packages that include unique wheels, tires and suspensions geared toward the great outdoors. We've also been informed that both trucks will offer diesel engine options starting in 2016, the only ones in their class. Well, it turns out those two great things may be going together. Poke around the stands of each of the brands and you'll find prototypes of both a Canyon All Terrain and a Colorado equipped with the 2.8-liter four-cylinder Duramax diesel. If they make it to showrooms, and we're told that they will, there will be nothing else like them on the dirt road. Fuel economy ratings for the trucks haven't been revealed yet, but the combination of these features has the potential to deliver some serious deep woods action. Now if GM would just throw in the six-speed manual available on the base models of the trucks...hey, a nerd can dream, right?