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2020 GMC Sierra HD Review

GMC has a new truck for 2020 just like its sister brand Chevrolet. I drove the Chevrolet Silverado HD in Bend, Oregon, not long ago, and I found it to be an excellent heavy-duty pickup. 

The GMC Sierra HD follows much of the same playbook as the Chevy, so you might expect me to say it’s just as good. I’m not going to say that. The GMC is better, but only slightly. GMC managed to take the same design as the Chevy and make it special enough to stand out. 

My Time With the Vehicle

The company invited me to Jackson Hole, Wyoming, to drive the new 2020 Sierra HD, the 2020 Sierra 1500 Duramax (a review of that truck will come at a later date), and the new 2020 Acadia AT4. I spent the better part of two days in the new HD. I spent time towing laden trailers, off-roading, and hauling a pile of logs all over the area. 

The GMC Sierra (at the time of this writing) trickled down to fifth place overall in truck sales below the Ford F-Series, Ram Pickup, Chevy Silverado, and Toyota Tacoma. This is for all versions of the GMC Sierra and not just the heavy-duty.

GMC tends to sell higher-priced machines and manages to cater to a more affluent customer. The Sierra’s unique offerings and its place in a more premium space of the truck market make it a very important truck for the segment. 

What Is It?

2020 GMC Sierra HD

The 2020 Sierra HD fits into the heavy-duty truck segment. It’s designed for buyers who have heavy loads to tow and haul.

The Sierra HD’s maximum conventional towing capacity is 20,000 pounds when properly equipped. Its max fifth-wheel towing capacity is 35,000 pounds when properly equipped. Its payload capacity is 6,532 pounds when properly equipped. Those aren’t the highest numbers in the segment, but they’re more than enough for the vast majority of buyers. 

When you look at the Sierra HD in terms of how it compares with the others in the segment, it’s a bit of an outlier in that the company purposely focuses on more affluent buyers. GMC sees itself as the only premium brand that sells exclusively SUVs and trucks.

Despite this, Ford, Chevy, and especially Ram all offer high trim levels of their trucks that are right on par with the Sierra HD. This comes down to marketing. GMC says it’s a premium brand, even if I were to say it was not, they still would claim to be higher in the food chain, but the lines get blurred once you compare the truck to the high trim levels of pickups from other automakers. 

In the end, all you need to know is that this is a nice truck built for people who want something with a little more prestige than a Ford, Chevy, or Ram. 

The Trims, Configurations, and Powertrains

2020 GMC Sierra HD

GMC like Chevy and the rest of the competition, GMC offers the Sierra HD in 2500 and 3500 variants. The truck can be had with a regular cab, double cab, or crew cab. You can get two- or four-wheel drive. A dually is also an option.  

As far as trim levels go, there’s the base Sierra, SLE, SLT, AT4, and Denali. The AT4 is the off-road version of the truck. It’s essentially the Chevy Silverado Trailboss of the GMC range, and it brings off-road equipment to the model while still providing ample towing prowess. 

In the GMC Sierra HD, you have the choice of two engines. They are the same choices as in the Chevy Silverado HD. There’s the 6.6-liter V8 gasoline engine that makes 401 hp and 464 lb-ft of torque. There’s also a Duramax 6.6-liter V8 turbodiesel that makes 445 hp and 910 lb-ft of torque. The diesel is the engine everyone wants and the one you should buy. 

The Exterior

2020 GMC Sierra HD

One of the GMC Sierra HD’s best qualities is its exterior styling. The truck is truly handsome in an age when most HD trucks look like a big ass air conditioner on monster-truck-sized wheels. Ford and Chevy have distinct—but I think ugly—styling right now. Ram is doing better, but GMC takes the cake. 

The exterior of the HD is bold. The design folks at GMC told me the beltline of the vehicle was actually brought down to improve sightlines. That lower beltline also looks better to me. The top of the bed was also brought down to improve sightlines and make it easier to tow a fifth-wheel trailer without having to worry about damaging the top of the bed accidentally.

It’s a purposely crafted design that’s also pleasing to the eye. GMC left the side of the doors smooth so you can put your company logo on the door easily. They could have gone funky with the sheet metal but chose not to. 

When I look at the GMC, I appreciate the level of restraint. The big chrome grille can seem a little gaudy on certain trim levels, but otherwise, this is an HD truck with class. 

You can say similar things for the AT4 off-roader. The truck features a blacked-out aesthetic. I’m not one to say that black equals rugged, but I do think it looks good. GMC didn’t go over-the-top as Ram does with the Power Wagon. Again, it’s a bold and somewhat sophisticated look. The AT4 has a little more attitude, but it doesn’t scream at you. 

There are two elements of the GMC Sierra’s exterior you really need to know about. The first is the company’s MultiPro Tailgate and the CarbonPro bed. The MultiPro Tailgate is a unique tailgate that offers six different functions and can be fitted with a Kicker audio system. 

The CarbonPro bed is the first carbon fiber bed in the industry. It’s supposed to be stronger than comparable steel or aluminum beds. I think it’s great, but it won’t be an inexpensive thing to replace if it does get damaged.

2020 GMC Sierra HD carbon pro bed

GMC gave us a chance to beat the heck out of the bed with bats, golf clubs, cinder blocks, and more. I managed to break a golf club on the bed and in the process put a crack in it (pictured above). Other folks’ attempts to damage the bed proved futile. It’s tough, and something GMC will be talking up until the competition gets on their level. 

These two special features set the GMC apart, especially in terms of GM products. They’re exclusive to the brand.

The Interior

2020 GMC Sierra HD Denali
Image from GMC

The interior is where GMC struggles—this is true of Chevy, too. Ram and Ford have better offerings.

This is specifically true when it comes to interior materials. I would love for GMC to put real wood trim in the cabin. Fake wood cheapens the whole cabin. Also, I don’t know where GM gets some of its plastics. Some of the plastic in the vehicle looks and feels cheap, but it’s not every bit of plastic.

It’s supposed to be a premium truck. Cheap plastic pieces on the doors and center console are a bad idea and are the chief contributing factor to me questioning whether it really deserves its premium branding.

The GMC Sierra HD should have real aluminum and wood trim. Some of the materials inside the cabin are top-notch. There is some aluminum (or what feels like it) and the leather is thick and soft. There will still be plastics because you have to in some cases, but the paper-thin flip-up covers on the auxiliary power outlets have to go, the cheap-feeling fake wood plastic trim needs to disappear, and the center console should be a thing of beauty. Leave the cheaper materials to low trim level Chevys where they belong. 

Towing Technology

2020 GMC Sierra HD
Image from GMC

GMC and Chevy have the same technology when it comes to towing, so if you read my Silverado review, you’re not going to see anything new here. 

Basically, it’s class-leading. There are tons of cameras installed on the truck and you get up to 15 different views from these cameras that all help make towing, seeing in blind spots, and generally doing about anything extremely easy. 

The coolest view is the one that essentially makes the trailer disappear. The image is stitched together from various camera angles. It looks mildly distorted but it’s honestly freaky helpful when driving.

In addition to that, you can set up to five distinct trailer profiles and there’s even a guest option if you borrowed a trailer from someone. All of this tech interfaces with GMC’s app, which connects your smartphone to your truck. If you’re towing an RV, there are even connections to equipment in the RV, which is awesome. You can adjust the climate control the RV while running down the road if you want. 

The Rest of the Technology

2020 GMC Sierra HD Denali
Image from GMC

The rest of the technology is standard GM. You get a large touchscreen infotainment system with one of the better interfaces out there. 

The infotainment system comes with 4G LTE Wi-Fi, Apple CarPlay, Android Auto, navigation, OnStar features, and more. It’s easy to use and there’s a lot to it. Pair that with all of the towing tech and driver aids like blind-spot monitoring and you have a technologically advanced truck that can do just about anything. 

How Big Is It?

2020 GMC Sierra HD profile

The GMC Sierra HD is, as you’d expect a big truck to be, extremely large. The truck measures 250 inches with the crew cab and long box and 266 inches with the long bed (about 22 ft long). It feels big on the road, but not unwieldy. GM has done a good job of making its big trucks easy to manage. Also, the technology helps a lot. 

You will have trouble getting this truck in a typical garage. However, that can be said of all HD trucks these days. They’re all large, and the GMC isn’t really any larger than its competition. The tucks are big and meant to be. 

One note on size is that the carbon fiber bed that GMC has in its vehicle allows for excellent cargo volume even with the lower beltline. The company managed to make sure there was no extra space between the interior of the bed and the exterior of the truck’s body. By removing that space, the bed is truly cavernous. 

Does It Work?

2020 GMC Sierra HD

I towed a 12,000-pound trailer up and down mountain roads, towed 30,000 pounds at one point around a small course, went off-roading at a 300-acre ranch, and hauled 2,000 pounds of logs up and down the mountains around Jackson Hole. 

So, does it work? Yes. Just like I expected. The GMC Sierra HD works as well in every regard as the Silverado HD. The engines, technology and much of the interior are the same. It’s more attractive in my opinion, and the Multi-Pro tailgate and optional Carbon-Pro bed help make the model more than most other pickups on the road. 

Is it perfect? Of course not. It suffers from many of the same minor pitfalls as the Silverado HD and fails at greatness if only slightly. The truck is good, darn good, and will get the job done for anyone with a large box trailer, horse trailer, or camper to tow. Still, there are some things I would gripe about. 

First and foremost is the cheap-feeling plastic inside the cabin. Most of the cabin materials are top-quality, but the cheaper pieces of plastic in this truck have to go. It’s a premium truck. It needs to lose the cheap fake wood (how about real wood?) and eliminate any cheap plastic in the cabin. 

Then there’s the question of if GMC’s truck is really a more premium product. It certainly caters to that audience, but the differences between GMC and Chevy feel small and I wonder if that’s really enough to justify GMC saying it’s a premium automaker. 

These are nitpicks. This HD pickup is an excellent machine and a true beast. It tows heavy loads with ease and the camera system makes doing so easier and less stressful than ever before. 

Does It Justify Its Price?

2020 GMC Sierra HD

If you’re reading this review and you like all the stuff mentioned above but don’t need a fancy tailgate, a carbon bed, or then buy the Chevy Silverado. It’s ugly, but you’ll save money going with the Chevy. 

The GMC Sierra HD in its most basic form is $37,195 for the 2500 regular-cab long bed. This is more expensive than the competition by about $1500 at the very least. As you climb the ladder the GMC stays more expensive. 

Most of the trucks I drove (there were several) were priced around $80,000. This is typical for a true HD towing machine these days regardless of manufacturer. These models came with some of the best tech in the business and most of the best features. 

So, if you want some prestige, a bit more of a luxury overall feel, better looks, and access to some fancy features like the CarbonPro bed and the Multi-Function tailgate, then the GMC may just justify its price. 

I’d consider saving some money by buying the Chevy. However, the Chevy is a true uggo, whereas GMC’s truck is handsome. The price delta might be worth it for that reason alone. Who wants to come out to an ugly vehicle every friggin morning? 

What’s the Verdict?

2020 GMC Sierra HD

In the end, it comes down to what you want. If you just want supreme power and excellent towing chops with the best towing assistance technology in the industry, then you buy the Chevy Silverado. 

If, however, you want your HD truck with a bit more prestige, for it to not look like it got beat with an ugly stick and have access to fancy things like a carbon-fiber bed and a new tailgate design, then you buy the GMC. 

Then we have the AT4. The closest competitor here is really Silverado Trail Boss or the Ram Powerwagon. The AT4 is an interesting proposition. It’s a heavy-duty truck that doesn’t suffer much in the towing and hauling department and can off-road like nobody’s business. If you need a towing machine, but also plan on doing some hardcore off-roading, GMC has your truck. 

In the end, you have to be ready to shell out some serious dough for a heavy-duty truck these days no matter what brand you choose. In terms of GMC, you have to decide if the small things that set it apart are worth it. There’s no doubt the truck is impressive but is it impressive enough? That is a question that each person will answer differently. For me, it is. 


  • Base Price: $37,195 (2500 regular cab, long bed)
  • Price as Tested: Prices varied but most were around $80,000
  • Drive Type: 2×4 and 4×4
  • Engine: 6.6-liter V8 or Duramax 6.6-liter V8 turbodiesel
  • Transmission: 6-speed automatic (gas engine), 10-speed automatic (diesel engine)
  • Power Output: 401 hp and 464 lb-ft of torque (gas engine), 445 hp and 910 lb-ft of torque (diesel engine)
  • EPA: NA
  • Optional Equipment: List not provided with vehicles driven
2020 GMC Sierra HD Review
Reader Rating1 Vote
Easy to use infotainment system
Attractive exterior
Strong engines
Excellent towing technology
Optional Carbon Pro bed
Unique optional tailgate design
Interior materials could be better
Not class-leading for horsepower or torque
More expensive than its Chevy Silverado cousin