2017 GMC Sierra Denali 2500HD Diesel: 7 Things to Know

GMC's biggest truck gains a bigger engine for 2017—but it's the overall package that impresses. 

GMC

The  GMC Sierra Denali 2500HD is part of a wave of vehicles that would have seemed oxymoronic not all that long ago: the luxurious heavy duty pickup truck. GMC, Ford, Chevrolet, Dodge, and Nissan all offer heavy duty rigs with the sort of comfort and conveniences features usually found on high-end cars: leather upholstery, heated and ventilated seats, upscale stereos with touchscreen controls, and so forth. It's a far cry from the days when big trucks were seen as simple tools, barely a step above military transports. 

But so long as people like these bougie trucks (which they seem to do), and as long as they make their companies big profits (which they definitely do), then GMC and all the rest are likely to keep on cranking out increasingly fancy heavy duty trucks

For 2017, however the big news in General Motors's truck world lies not in the cabin, but under the hood. Sierra HD models (along with their corporate brothers in the Chevy Silverado lineup) gain a new 6.6-liter Duramax turbodiesel V-8, which cranks out 445 horsepower and—more importantly for diesel customers—910 pound-feet of torque. Which, by most objective measures, would be more than enough to drop jaws...if the Ford Super Duty's diesel didn't make even more torque. 

1. The Sierra Denali may not make the biggest numbers—but they're still damn big

GMC says it stresses confidence over capability when it comes to its heavy-duty trucks—which is to say, the brand knows it isn't going to beat Ford's bonkers Super Duty when it comes to towing claims. But since the vast majority of HD truck owners actually never tow more than 20,000 pounds, the truck maker aims to make hauling cargo as easy as possible for the average Joe rather than chase record-setting numbers.  

That's not to say the Denali's stats are insignificant. The 2500HD version can tow up to 15,400 pounds—just shy of eight tons—or haul around 3,233 pounds of people and cargo. 

2. The GMC's diesel engine is loud and proud

Some diesels these days try to hide their oil-burning nature behind acoustic insulation and other auditory trickery. Not the Sierra HD. The truck clatters like a fire truck when you dig into the throttle at low speed; it's clearly audible even inside the Denali's otherwise quiet cabin. But considering the  pride this truck seems to have in its powertrain— "DURAMAX" badges on the hood are large enough to earn a nod of approval from Flava Flav—the noise feels more like a feature than a bug.

3. The Sierra Denali HD handles better than you'd expect

It may weigh more than 6,500 pounds and the steering's a little light, but if you trust in it, it'll claw through corners with surprising tenacity. It's certainly more nimble than you'd expect for a truck this size that packs a suspension made to handle a 9,500-pound GVWR

4. It tops out at 98 mph

But that feels like 60. It's rock steady at that speed. And it feels like it could go a whole lot faster, if the governor—there to protect the tires, a GM spokesperson said—weren't there to stop the fun. 

5. Tech is good for this truck 

The truck's systems all work in concert to make towing easier. The cruise control, engine brake, and stability control are all designed to handle the tasks of hauling around big trailers. And there are both rear- and side-view cameras, the latter of which kick on whenever the turn signal activates. (You can also manually bring them online anytime using the infotainment system, which is kind of neat.) 

6. Diesel fuel mileage is well-regarded for a reason

The 2500HD Sierra, like all heavy-duty pickup trucks, is large enough to keep the EPA from posting fuel economy numbers on the window sticker. But the truck's trip computer said this almost-four-ton brute managed nearly 17 miles per gallon over an 80-mile stretch—a stretch that included some high-speed blasts. 

7. It deserves a better horn

While testing the Sierra Denali HD out in the western boonies of Colorado, I came over a hill at highway speeds—only to find free-ranging cattle walking around less than six feet from the road. I laid on the horn to warn them off...only to be greeted with the same sort of note you'd hear out of a Chevy Malibu. A truck this big and beefy deserves an air horn. Or at least something an octave or two lower than the sound that comes out of a passenger car.