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2020 GMC Sierra HD first drive review: Towing tech marvel With a bevy of cameras, an in-vehicle checklist and a cool app for your phone, the all-new Sierra Heavy Duty has got your trailer covered.


There was a time when trucks were a basic tool of the common worker. Not much thought was given to ride quality or comfort. Luxury? Technology? That's for your fancy sedan, pal.

Fast forward to today and trucks are more useful than ever while also being incredibly luxurious and tech-rich. And perhaps no truck does a better job of being everything to everyone than the newest generation of the GMC Sierra Heavy Duty. This is a truck made for work, but tacks on myriad features that make work both easier and less stressful.

2020 GMC Sierra HD
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2020 GMC Sierra HD

A new AT4 trim means you can get your HD fix on the dirt.


Not only is the heavy duty lineup new from the ground up for 2020, but it also gets a new off-road focused AT4 trim. The AT4 doesn't offer a suspension lift over the Sierra, SLE, SLT or Denali trims -- in fact, it includes the same Rancho shocks, skid plates and electronic locking rear differential as the aforementioned Denali. However, it does include an off-road mode and all-terrain tires wrapped around 18-inch wheels. After playing around a bit I found the tires did fine in the dry dirt, but if mud is on the agenda, you should definitely upgrade. 

Overall, the Sierra HD doesn't share a single body panel with its predecessor. It's taller and has a longer wheelbase than before, with a massive grille and redesigned LED lighting all the way around. The bed is an inch lower for easier loading, side steps are included for easier access to the bed and the kick-ass MultiPro six-way tailgate is available on all trims. I'll get back to the tailgate later, but now I want to focus on what the Sierra HD does best: towing.

Tow it with ease

The Sierra's executive chief engineer, Tim Herrick, says, "I want my GMC Sierra to be the trailering truck of choice," and man, is this guy on the right track. The optional 6.6-liter V8 diesel engine puts out 445 horsepower and 910 pound-feet of torque so the Sierra HD can tow 35,500 pounds with a fifth wheel or 20,000 pounds worth of conventional trailer, and can manage 6,532 pounds in its bed. If you're keeping track, that's more towing capability from heavy-duty trucks from Ford and Ram, even though both manufacturers' pickups feature more engine torque.

There is a 6.6-liter V8 gas option as well, pushing out 401 horsepower and 464 pound-feet of torque. As expected, the towing numbers go way down here, but it can still handle much of what consumers would need: 17,400 pounds with a fifth wheel, 16,800 pounds using a conventional trailer, 7,442 pounds of payload.

In the mountains of Wyoming around Jackson Hole, I spend my time in the diesel towing all the heavy things: a 40-foot long, 14,000-pound fifth wheel; a 30-foot, 13,000-pound conventional box trailer; and the grand-daddy of them all, 35,500 pounds worth of steel plates and, hilariously, competitors' tailgates. (GM does love a good PR stunt.) Certainly, the weight slows the truck down, but all the diesel torque is available right off the line, so getting up to speed isn't a problem, even at 6,000 feet of elevation. On the opposite side, hitting the brakes reveals smooth pedal feel and no funny business from the trailer. 

2020 GMC Sierra HD
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2020 GMC Sierra HD

It's like x-ray vision!


Where GMC really knocks it out of the park, however, is with its trailering tech. Blind-spot monitoring that covers the length of the trailer is eschewed for a six-camera setup, or eight if you opt for two dealer-installed accessory cameras inside and at the rear of your trailer. All told, you can get 15 different views of what's going on around the truck and trailer, including side views, a view of the hitch and a view inside the trailer.

GMC goes for the hat trick, however, with the transparent trailer technology that stitches together the view from the accessory camera in the back of the trailer with the tailgate-mounted camera, essentially allowing drivers to see through their trailer. No longer will you wonder how many cars are stacked up behind you on that mountain road, so you have no excuse for not using the turnouts. Now that I've pulled a trailer with this tech, I can't imagine towing without it.

The in-vehicle trailering app provides a convenient way to check on the trailer. Before heading out on a drive I can see my trailer's tire pressures and temperature, check the taillights and go through a checklist to be sure I've completed every task necessary to safely hook up a trailer

Other trucks offer a similar checklist feature, but again, GMC goes one step further with the MyGMC app. Accessible from your phone or through the standard Apple CarPlay or Android Auto interfaces, drivers can control a properly equipped trailer's HVAC system and check water, propane and grey/black water levels. Imagine pre-warming your camper 15 minutes before pulling into a campsite and having it nice and toasty upon arrival.

2020 GMC Sierra HD: The big boy

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Solid ride 

The diesel V8 is mated to a 10-speed automatic transmission. This is the first time a 10-speed has made its way to the heavy-duty pickup segment, and it performs like a champ, getting the most out of the engine and shifting smoothly up or down as necessary. The diesel engine is quiet, even on take off, though GMC increased cooling for 2020 by adding a dual-path air intake system and it's pretty loud, so the result is actually more powertrain noise than before.

While other heavy-duty trucks feature a solid axle in both the front and the rear, the Sierra HD opts for an independent front suspension. GMC says it's more durable over the long haul, and in my testing, it offers great ride quality both with or without a load behind you. A four-wheel-drive automatic gear is added to the two-speed transfer case, which should help when you need a little more traction, but not enough to warrant high-gear four-wheel drive.

MultiPro tailgate, first seen on the light duty Sierra, is a Roadshow favorite and makes its way to the Sierra HD. It can open like a regular tailgate with a flip-up load stop but then transforms into a work surface or a step with a soon-available Kicker audio system. The center section can drop to allow easier access to the bed.

2020 GMC Sierra HD
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2020 GMC Sierra HD

Anyone need a log cabin built?

Emme Hall/Roadshow

The Sierra HD has a few other cool tricks not found elsewhere, like a 15-inch color head-up display and General Motors' cool rear camera mirror so you can still see behind you even with two dirt bikes in the bed.

Same ol' interior

Inside, the cabin is pure function over form. It's comfortable and everything is within reach, but I wouldn't say it has any distinctive style as you'll find in the Ram heavy-duty trucks. GMC's infotainment system is housed on an 8-inch screen and is one of the easiest in the business to navigate. Apple CarPlay and Android Auto are standard as is a 4G LTE WI-Fi hotspot. There are plenty of charging options, from a wireless pad to USB Type-A and Type-C ports, as well as 120-volt outlets.

Of course, none of this comes cheaply. The diesel engine adds over $9,000 to the Sierra HD's $40,000 base price, plus $1,595 for destination. However, the popular AT4 trim starts at $57,700 while the Denali will set you back $63,700 to start. All the trucks I drove at the media launch were close to $80,000, thanks to their many technology upgrades. 

Regardless, the pricing is still competitive within the heavy-duty truck segment. And the Sierra HD offers more technology to make the most of its class-leading towing capability. Look for single- and dual-rear-wheel configurations to hit dealers any day now.

2020 GMC Sierra HD
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2020 GMC Sierra HD

The cabin of the Sierra HD is functional, but far from attractive.


Editors' note: Travel costs related to this feature were covered by the manufacturer. This is common in the auto industry, as it's far more economical to ship journalists to cars than to ship cars to journalists. While Roadshow accepts multiday vehicle loans from manufacturers in order to provide scored editorial reviews, all scored vehicle reviews are completed on our turf and on our terms.

The judgments and opinions of Roadshow's editorial team are our own and we do not accept paid editorial content.

Originally published Aug. 25.
Update, Aug. 26: Removes information about CarbonPro bed, which GMC confirms is not available on Sierra HD models.