A step-up over the previous model in almost all the departments

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GMC trucks are like the school students who don’t top the class, but they don’t fail either. They are never in the spotlight for good or bad reasons, with the exception of when the Sierra debuted with that new MultiPro tailgate. The GMC Sierra HD has been living in the shadow of its competition, the Silverado HD, and despite having a lot of things in common, it has never been able to trump the Chevy. However, it looks like the Sierra is trying to break those shackles with the 2020 model. The Sierra HD looks to have gotten rid of its flaws, and this time, it promises to be a well-packaged truck that can prove to be a serious threat to the competition.

2020 GMC Sierra HD Exterior

  • New, controversial grille
  • Taller Hood
  • Slightly taller
  • Longer wheelbase
  • MultiPro tailgate
  • 15 trailering cameras
2020 GMC Sierra HD Exterior
- image 817264

The GMC Sierra HD just cannot be ignored due to its sheer size and presence. The bold, in-your-face grille is more than enough for people to sway their cars away when they spot it in their rearview mirrors.

The Sierra went through a generational shift in 2019, and that facelift has now carried over the 2500 and 3500 HD models.

So in terms of looks, the Sierra HD now looks as up to date as its 1500-badged little brother. The awful chrome grille makes it way over here as well, but due to the truck’s size, one can live with it, unlike the latest BMWs. The hood is taller, has a chrome lip, and a fully-functional hood scoop to cool off the humongous engine underneath. The muscle lines on the hood add to the butch look of the truck. As for the headlights, they are the same, large-sized units with C-shaped LED housing and daytime running lights.

2020 GMC Sierra HD
- image 818478

The side profile looks rather clean when compared to the garish front.

The 2020 GMC Sierra HD has a raised stance, thus making the huge wheels look quite small, especially with that black plastic cladding.

The side view mirrors are a size larger this time and come with the engine badge stamped right behind it. The 2020 GMC Sierra HD comes with a longer wheelbase and is taller than the outgoing 2019 GMC Sierra HD.

Now, let’s get to the talking point of this truck. The rear of the 2020 GMC Sierra HD is as generic as it can get but still looks smarter than the competition. The brand badge is prominent and placed on the center of the tailgate. The GMC Sierra HD comes with not one or two, but 15 cameras in total to give you an action of what’s going on around its body.

The six-mode tailgate, that GMC likes to call the MultiPro tailgate, can work as a standing desk or can be folded down to create a step into the bed. The MultiPro tailgate is rated and can support up to 375 pounds.

GMC Sierra HD Exterior Dimensions

Double Cab Crew Cab
Wheelbase (in. / mm): 144.2 / 3662 – 6’6” box
158.1 / 4017 – 8’ box
153.7 / 3904 – 6’6” box
167.7 / 4258 – 8’ box
Overall Length (in. / mm): 230 / 5842 – 6’6” box
248.9 / 6322 – 8’ box
239.5 / 6083 – 6’6” box
258.4 / 6563 – 8’ box
Overall Width (in. / mm): 80.5 / 2045 80.5 / 2045
Overall Height (in. / mm): 78 / 1983 (4WD w/ 6’6” box)
77.9 / 1978 (2WD w/ 8’ box)
77.8 / 1977 (4WD w/ 8’ box)
78.2 / 1988 (2WD w/ 6’6” box)
78.2 / 1987 (4WD w/ 6’6” box)
78 / 1981 (2WD w/ 8’ box)
77.9 / 1980 (4WD w/ 8’ box)

Note: 2019 GMC Sierra HD exterior dimensions listed here.

2020 GMC Sierra HD Interior

  • Best-in-class headroom
  • Best-in-class legroom
  • Trailering system makes backing up easy
  • iN-Command system provides remote control of some features
2020 GMC Sierra HD
- image 817279

Gone are the days when trucks used to have basic, barebones interiors. The kind of cabins trucks have these days can put luxury sedans to shame.

The GMC Sierra HD comes with a posh cabin that exudes nothing but sheer class and quality, and even has best-in-class front headroom and legroom in the Crew Cab models.

Talking about the cameras, GMC has capitalized on a basic problem that all truck owners with a hitched ride face. Surprisingly, no other automaker has worked as in-depth to make lives of owners easy. Remember the scene from Fast and Furious 4 where Dom and crew tried to steal the oil tankers? Well, this technology would have changed the whole scene. Anyway, GMC has offered 15 cameras that help drivers see what’s around the truck and the trailer. The 2020 GMC Sierra HD even lets the driver see right through a trailer by stitching together footage from a camera mounted on the tailgate and footage from an accessory camera that needs to be installed on the back of the trailer. This makes navigating the parking lots, merging into traffic or making tight turns a breeze.

2020 GMC Sierra HD
- image 817282

The 2020 GMC Sierra HD also comes equipped with the iN∙Command control system that provides the ability to monitor and control select functions of equipped trailers through the myGMC mobile app. For instance, if it’s a camper, they can use the app to turn on the A/C or the water heater, check the water level, and check the generator’s fuel level.

With a second app called "Trailering," owners can also verify the trailer’s tire pressure, whether the lights work, and access a pre-departure checklist.

Of course, this all depends on whether or not your trailer is actually compatible with the iN-Command system, so those of you still rocking out those 1980s campers probably won’t find this of interest.

2020 GMC Sierra HD
- image 817294

Other features include:

  • Rear Camera Mirror technology from the Cadillac CT6
  • 15-inch-diagonal head-up display
  • Android Auto and Apple CarPlay support
  • Auto Electric Park Brake
  • Park Grade Hold Assist
  • Hill Start Assist
  • Hill Descent Control
  • Trailer Sway Control

GMC Sierra HD interior dimensions

Double Cab Crew Cab
Headroom (in. / mm): 42.8 / 1087 (front)
38.7 / 982 (rear)
42.8 / 1087 (front)
40.5 / 1029 (rear)
Legroom (in. / mm): 45.3 / 1150 (front)
34.6 / 880 (rear)
45.3 / 1150 (front)
40.9 / 1040 (rear)
Shoulder room (in. / mm): 64.8 / 1647 (front)
64.3 / 1634 (rear)
64.8 / 1647 (front)
64.3 / 1634 (rear)
Hip room (in. / mm): 60.7 / 1543 (front)
60.2 / 1530 (rear)
60.7 / 1543 (front)
60.2 / 1530 (rear)

Note: 2019 GMC Sierra HD interior dimensions listed here.

2020 GMC Sierra HD Drivetrain

  • 6.6-liter Duramax or 6.6-liter V-8
  • Up to 445 horsepower
  • As much as 910 pound-feet of torque
  • Towing capacity of more than 30,000 pounds
  • Estimated 7,500-pound payload capacity
  • 10-speed Allison transmission with Duramax
  • Six-speed auto with entry-level gasonline engine
  • Ram and Ford HD trucks can tow more
2020 GMC Sierra HD
- image 818475
For a truck like the Sierra HD, you need something really powerful under the hood. GMC has plonked the 2020 Sierra HD with a 6.6-liter, V-8 Duramax turbocharged engine that produces 445 horses and 910 pound-feet of torque.

Although 910 pound-feet of torque is more than adequate, we wonder why GMC did not try to top the new Ram HD’s 1,000 pound-feet of torque. GMC is selling this as a heavy-duty hauler; so this would have been a great selling point for the automaker. The engine is mated to 10-speed automatic transmission. A gasoline engine will also be offered, but all we know about it is that it a new unit that is mated to a six-speed automatic transmission system so don’t expect efficiency to be a big selling point.

2020 GMC Sierra HD Exterior
- image 817285
The company has not announced exact trailer ratings and towing capacity, but GMC has said that the 2020 Sierra HD will be able to lug in excess of 30,000 pounds.

Although this is an improvement over the 2019 Sierra HD, which could tow 23,300 pounds, it falls short of the Ram’s 35,100-pound rating and, perhaps, even the Ford F-Series heavy-duty trucks which can lug 32,000 pounds.

{{GMC Sierra 3500 HD}} {{Ram 3500 HD}} {{Ford F-450 Super Duty}}
{{Engine}} 6.6-liter Duramax 6.7-Liter Cummins 6.7-Liter Power stroek
{{Transmission}} 10-Speed Allison Six-Speed Auto Six-Speed Torqshift
{{Horsepower}} 445 HP 400 HP 440 HP
Torque 910 LB-FT 1,000 LB-FT 925 LB-FT
{{Curb Weight} TBA TBA 7,000 LB +
{{Maximum Towing Capacity}} 33,000+ LBS 35,100 LBS Up to 35,000 LB
{{Payload Capacity}} TBA 6,570 LBS 7,640 LB
{{GMC Sierra 3500 HD}} {{Ram 3500 HD}} {{Ford F-450 Super Duty}}
{{Engine}} 6.6-liter V-8 (gasoline)(est) 6.4-Liter HEMI V-8 6.2-Liter Flex V-8
{{Transmission}} Six-Speed Auto (est) Six-Speed Automatic Torqshift Six-Speed Auto
{{Horsepower}} 400 HP (est) 410 HP 385 HP
Torque 450 LB-FT (est) 429 LB-FT 430 LB-FT
{{Curb Weight} TBA TBA 5,668 to 7,526 LBS
{{Maximum Towing Capacity}} 18,000 LBS (est) 17,980 LBS 13,300 LBS
{{Payload Capacity}} TBA TBA 2,474 to 4,332 LBS

2020 GMC Sierra HD Pricing

2020 GMC Sierra HD
- image 817270

Although the pricing has not been revealed, we speculate it to be in the ballpark of $42,000 for the 2500 HD, and $44,000 for the 3500 HD, thus undercutting the competition by a slight margin. Add on all the options and you could easily eclipse the $50,000 mark. The 2019 GMC Sierra 2500HD and 3500HD came with a price tag of $38,000 and $40,000, respectively.

2020 GMC Sierra HD Competition

Ram HD

2019 Ram Heavy Duty Looks Menacing, Pumps out 1,000 Pound-Feet! Exterior
- image 814465

You think the GMC Sierra HD has a big mouth? Well, look at the grille on the Ram HD. This is a grille that can even give the new breed of Bimmers a complex. The Ram HD literally transformed itself from a beast to a monster. Under the hood of the Ram HD is a 6.7-liter, Cummins, turbodiesel that produces a mammoth 1,000 pound-feet of torque, but a mere 400 horses. However, Ram offers it with a six-speed transmission only, thus limiting its potential to a certain extent. The same unit is available with a lower power rating as well with just 370 ponies and 850 pound-feet of torque. The base trim is powered by a 6.4-liter Hemi V-8 engine that produces 410 horsepower and 429 pound-feet of torque. The automaker has reworked its chassis and body, which enabled it to shave off 143 pounds of curb weight when compared to the previous model. With all extras added, the Ram can pull 35,100 pounds and deliver a payload of 6,570 pounds. It can be customized with a rear air suspension which can be very helpful while loading and unloading.

On the inside, it may not seem as lush as the GMC Sierra, but Ram has offered all the creature comforts. The console area is now 22.6 liters, 2.9 liters larger than the 2019 model, and includes 12 storage configurations. In short, it can now hold bigger items like tablets. The base trim comes with a five-inch infotainment system, while the higher trims can be availed with an 8.4-inch or and 12-inch screen. It also comes with five USB ports, three 115-volt plugs, and wireless charging docks.

Read our full review on the 2019 Ram 2500 Power Wagon.

Ford Super Duty F-250

2017 Ford Super Duty High Resolution Exterior
- image 648383

As is the norm in this segment, the Ford Super Duty F-250 also comes with a huge chrome grille slapped on its face. It is offered with two different engines - a 6.2 liter, V-8 engine that develops 385 horses and 430 pound-feet of torque and a 6.7-liter, turbodiesel V-8 mill that churns out 440 ponies and 925 pound-feet of torque. Impressive? Not really, but we would say it’s on par with the competition. Both engines come mated with a six-speed automatic transmission, either in two-wheel-drive system or four-wheel-drive configuration. Towing capacity is rated at 32,000 pounds when properly equipped!

On the inside, the truck is a typical Ford - large, comfortable, and utilitarian. The top-trim comes with an 8-inch touchscreen infotainment system, leather upholstery, power-adjustable pedals, and heated and cooled seats, to name a few. As is with any Ford truck and SUV, there is not dearth of customisation. Right from spoiling yourself with creature comforts, to mechanicals, Ford has made sure you can build this truck as per your convenience. However, this could see you shell you out more than $80,000 if you check out all of the options boxes.

Read our full review on the 2018 Ford Super Duty F-250

Final Thoughts

2020 GMC Sierra HD Exterior
- image 817274

The 2020 GMC Sierra HD comes with a few, but very practical changes; like the 10-speed Allison transmission system that can make driving with heavy loads a little more sprightly and peppy. Features like the 15-inch head-up display, 15-camera setup and its compatibility with apps, and a multi-mode tailgate that makes things a lot more interesting in day-to-day use. The 2020 GMC Sierra HD will be built at the company’s Flint Assembly in Flint, Michigan and is set to arrive in summer of 2019. Based on history, the GMC has sold 50-percent of its trucks in the Denali trim. With a lot more potential this time around, do you think the 2020 GMC Sierra HD can sway the Ford and Ram customers to opt this beast? Share your thoughts with us in the comments section below.

  • Leave it
    • Looks may not be to everyone’s liking; too much of chrome application
    • Towing capacity, although not revealed officially, should have been more than Ram HD’s 35,000 pounds
    • Can get quite expensive with add-ons

Further Reading

2019 GMC Sierra Exterior
- image 771288
The 6.2 and 5.3-liter were updated

Read our full review on the 2019 GMC Sierra.

Sidd Dhimaan
Sidd Dhimaan
Senior Editor, Truck Expert, EV Expert - sidd@topspeed.com
Sidd joined the Topspeed.com team in 2017 as an intern and in less than a year he earned a full-time position as an associate editor and junior automotive expert. Fast forward to today, and he is currently serving as a senior editor, pickup truck expert, and EV expert.  Read full bio
About the author

DETROIT — Bigger, stronger and smarter, the all-new 2020 GMC Sierra Heavy Duty combines greater trailering capability with technologies designed to provide customers with a world-class towing experience.

“The all-new 2020 Sierra HD is the most capable heavy-duty truck that we’ve ever offered,” said Duncan Aldred, vice president of Global GMC. “For customers who demand a premium, innovative heavy-duty truck that supports their passions, the next-generation Sierra HD can pull like a pro.”

Form and function come together in the new Sierra Heavy Duty, with features that include:

An enhanced ProGrade Trailering system featuring class-leading available 15 camera views, including a segment-first transparent trailer view to virtually see through a trailer in tow.1
An available smart trailer designed to integrate the iN∙Command® control system from ASA Electronics2 provides the ability to monitor and control select functions of compatibly equipped trailers through the myGMC mobile app3.
A segment-exclusive available 15-inch-diagonal head-up display that offers useful trailering information, including vehicle speed, navigation information and an inclinometer display for the road grade.
An available segment-first Rear Camera Mirror.
MultiPro, the world’s first six-function tailgate, allows easier loading, unloading and bed access and is available on all trim levels.
A larger, commanding design that provides more room for cargo and occupants.
Best-in-class Crew Cab front headroom and legroom for the driver and other front-row occupants.
An all-new, segment-first, Allison 10-speed automatic transmission mated to the legendary 6.6L Duramax turbo diesel.
For those looking to take refined capability off-road, GMC fortifies the new AT4 brand with an all-new Sierra AT4 Heavy Duty available for Crew Cab configurations as both a 2500 and 3500 single rear wheel offering.
With more than half of Sierra HD customers choosing Denali, it continues to offer the ultimate expression of professional grade materials and refinement. The all-new model delivers power, intelligence and segment advancements to meet the needs of heavy-duty customers with discerning taste.

ProGrade Trailering Technology
First introduced with the 2019 Sierra light duty, the ProGrade Trailering System leverages technology advancements to offer additional features and functionality for the 2020 Sierra Heavy Duty.

“Trailering is the most important consideration for Sierra Heavy Duty customers, and the new features and technologies in the 2020 Sierra HD make it easier than ever to hitch a trailer and tow it confidently,” said Jaclyn McQuaid, vehicle chief engineer, Heavy Duty Trucks. “We’ve developed this new truck to offer the greatest trailering experience ever offered by GMC.”

An available class-leading 15 unique camera views1, including an industry-first transparent trailer view, help optimize the driver’s view around the truck and compatible trailers to provide added confidence when towing. The revolutionary transparent trailer feature uses the tailgate-mounted camera and an available accessory camera mounted on the rear of the trailer. The resulting display helps the driver to virtually see through the trailer4, a benefit when navigating parking lots, merging into traffic or making tight turns.

Owners of the 2020 Sierra HD will have access to available smart trailer technology designed to allow access to select features of the iN∙Command® control system from ASA Electronics2 through the myGMC mobile app, either on compatible Android and iOS smartphones or on the vehicle’s infotainment system via Apple CarPlay5 or Android Auto6. Similar to the features of a smart home, the iN∙Command® control system acts as the central hub of operations to monitor and control an array of systems in trailers equipped with the next-generation technology. Depending on how a compatibly equipped trailer is configured, owners of the 2020 Sierra HD may be able to turn on the trailer’s air conditioning or water heater, check water and holding tank levels, or monitor fuel levels on trailers equipped with generators — all before arriving at their destination.

The ProGrade Trailering System also includes an in-vehicle Trailering App7 with Trailer Light Test, Trailer Electrical Diagnostics, Trailer Tire Pressure and Temperature Monitoring, Pre- Maintenance Reminders and Departure Checklist. Many of the Trailering app’s functions, including the lighting test and pre-departure checklist, are also available with the myGMC mobile app, a feature that offers great convenience when outside the truck or trailer.

Additional available technologies and hardware to aid trailering include:

Auto Electric Park Brake to automatically apply the parking brake to help maintain truck position when hitching.
All-new Park Grade Hold Assist enhances hill hold by using braking effort at each wheel for an extended period of time.
All-new larger, door-mounted trailering mirrors with a four-bar link providing power extend and retract for the driver and passenger sides.
Integrated trailer brake controller that works with the trailer profile in the Trailering App to recall a specified trailer’s most recent gain setting.
Tow/Haul mode that remains engaged on the next key-on cycle, for up to four hours; includes a reminder the feature is engaged.
Hill Start Assist and Hill Descent Control.
Trailer Sway Control.
Auto Grade Braking and Diesel Exhaust Braking.
Digital Variable Steering Assist that dynamically optimizes power steering according to driving scenarios, including trailering, and enables features like road pull compensation.
Trailering Info Label placed on the driver’s door jamb that clearly calls out the truck’s specific trailering information, including curb weight, GVWR, GCWR, maximum payload, maximum tongue weight and rear GAWR.8
Bigger and bolder
The 2020 Sierra HD has a commanding, powerful design rooted in a new architecture with larger proportions. It is taller and longer, with a more confident stance defined by a bold design that epitomizes GMC’s signature refinement and technologically driven attention to detail.

“We took every opportunity to visually express the strength and capability that lies beneath the surface,” says Matt Noone, director of GMC exterior design. “The elevated hood line, the strong shoulders, the striking front grille — these cues communicate the strength and performance that have been engineered and built into each and every Sierra Heavy Duty.”

The all-new Sierra HD is highlighted by new signature lighting, including prominent “light blades” that deliver LED illumination for the daytime running lamps. LEDs are also used for the headlamps, taillamps, available fog lamps and other illuminative elements, including the available roof marker lights standard on all dual-rear-wheel HDs and all Sierra HD Denalis except where prohibited by law.

Inside, the Sierra HD’s new interior has best-in-class front head- and legroom (maximum), with Crew Cab models. A higher seating position complements the truck’s taller profile to offer a confident view from behind the wheel. Additional optimized ergonomics emphasize easy, intuitive interaction with the vehicle’s available technologies, such as a heavy-duty segment-first head-up display and GMC’s latest touchscreen infotainment systems.9

Denali-exclusive materials — including premium leather-appointed seating, authentic open-pore wood trim and dark-finish aluminum decor — raise the interior’s refinement. The leather appointments have a distinctive, large-pebbled grain with a contrasting stitch pattern that is premium in appearance and touch without sacrificing durability, and the wood trim features an open-pore texture evocative of hand-planed furniture.

Compared to the current model, the new Sierra Heavy Duty has:

A longer wheelbase, a taller, more dominant hood line and taller overall height.
A larger grille and complementing functional hood scoop to feed an advanced cooling system for the Duramax turbo diesel.
Class-leading heavy-duty cargo bed volume10 and 12 corner tie-downs with a new, available 120-volt power outlet.
One-inch-lower bed lift-in height compared to the 2019 Sierra Heavy Duty, providing easier loading and fifth-wheel and gooseneck trailer hitching10.
New, segment-exclusive cargo bed side steps on all box styles, located in front of the rear wheel openings, that complement integrated CornerSteps in the rear bumper to improve access to the cargo area.
World’s first six-function MultiPro tailgate available on all trim levels and standard on SLT, AT4 and Denali.
All-new Sierra AT4 HD: Refined HD Capability Off-Road
The all-new 2020 Sierra Heavy Duty AT4 continues the AT4 brand’s growth with a distinctive off-road identity to complement its robust HD capability. Driven by dark chrome exterior finishes and contemporary detailing, Sierra HD AT4 features front and rear bumpers and a grille surround finished in body color. The bold grille design, with its rugged texture, is finished in black chrome and set off by the AT4’s distinctive red vertical recovery hooks.

The athletic interior also carries AT4-specific darkened trim, including dark-tinted and textured aluminum finishes on the steering wheel, center stack and sill plates, as well as a unique Jet Black interior with Kalahari color accents in the seats and live stitching. Leather-appointed seating, with mini-perforated inserts and embroidered AT4 badging on the headrests, along with all-weather floor liners, is standard delivering durability with uncompromising comfort.

The new Sierra AT4 Heavy Duty’s off-road capabilities are rooted in a unique suspension and supporting technologies that include:

Off-road suspension, Rancho Shocks, skid plates, Eaton locking rear differential.
Eighteen-inch wheels wrapped with Michelin all-terrain tires, with 20-inch wheels available.
Traction Select System with specific Off-Road mode.
Hill Descent Control and Hill Start Assist.
Segment-exclusive 15-inch diagonal Head-Up Display with Off-Road Inclinometer.
HD Surround Vision1 for low-speed views of vehicle surroundings.
Confident trailering power
GMC’s legendary Duramax turbo diesel and Allison Transmission pairing continues to offer the ultimate in towing confidence.

The proven Duramax 6.6L turbo-diesel engine offers high torque, high power, low noise and exceptional durability. For the 2020 Sierra HD, the Duramax offers an SAE-certified 445 horsepower and 910 lb-ft of torque. This already powerful engine performs more efficiently thanks to increased cooling capacity delivered in part by improved air induction. A dual-path intake system draws dense, cool air through both the prominent hood scoop and the larger front grille.

The new Sierra HD marks the introduction of an all-new 10-speed Allison automatic transmission — the first-ever offered in the heavy-duty pickup segment. The all-new 10-speed transmission with closer gear spacing allows the engine to operate in an optimal range at all times with varying load and terrain conditions.

The bigger frame, stronger propulsion and smarter technologies are expected to deliver dramatically greater towing capacity than previous models, well in excess of 30,000 pounds. More details regarding an all-new gas engine and trailering capabilities will be announced shortly.

Coming late summer 2019
The 2020 Sierra HD goes on sale later this year in 2500HD and 3500HD dual rear wheel and single rear wheel configurations. Pricing and complete specifications will be announced later.

With a $1.5 billion investment to support the next-generation Heavy Duty truck launch, Flint Assembly in Flint, Michigan, will proudly build the 2020 Sierra Heavy Duty.

View the full press release Hide press release
Press release

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