– Gateway, Colorado

The first time the Chevrolet Colorado ZR2’s stainless-steel rock rails screech against rubble on the Bangs Canyon off-road trail, I wince. But I needn’t worry about damaging those when I recall what Colorado engineer Tim Demetrio put them through. Unconvinced that the rails, which mount to the truck’s body instead of to the frame like most aftermarket units, would be strong enough, he tried – and failed – to break them.

“I was dropping the truck off ledges to bend them,” he says. Yet no matter what, the rails held tough.

That ethos explains exactly how Chevrolet approached the task of turning the ZR2 concept, shown at the 2014 Los Angeles Auto Show, into this production off-roading machine: Do everything right to improve capability and durability, not just for looks.

Visually, though, the most obvious difference is the new front fascia that exposes new wheels and tires to improve the approach angle significantly to 30 degrees (versus 17.1-17.7 for other models). The 17-inch wheels are unique to the ZR2, there are subtle ZR2 decals on the bed, and you can see the exposed aluminum skidplate that protects the engine and radiators. But as off-road specials go, the ZR2 is relatively subdued on the outside.

It’s underneath that Chevrolet pulled out the metaphorical big guns. New front control arms and steering knuckles, along with new rear leaf springs, help lift the ZR2 by two inches and increase its track width by 3.5 inches. Mechanical changes also in...