Ready for Heavy Off-Road Duty

A Victory & Reseda review of the 2020 GMC Sierra Heavy Duty pickup truck

When General Motors set out to create the newest generation of full-sized pickup trucks, they knew that they had to match the competition at their game. But, how?

The formula is simple: add lighter materials, more innovation, and up the ante on performance and capability.

A few months ago, I welcomed the 2019 GMC Sierra 1500 in the new AT4 trim. This particular pickup truck was a sampling of the latest GM had poured into its half-ton pickup truck. This truck featured the MultiPro tailgate with six configurations to use. It also featured the latest in cylinder deactivation with Dynamic Fuel Management that can bring the number of active cylinders down to two. Then, there’s the mix of high-grade steel, aluminum, and other materials to bring the overall weight of the truck down a couple of hundred pounds compared to the previous generation.

2020 GMC Sierra 2500HD Crew Cab 4WD AT4

It was good to experience all of these innovations. Yet, I was left wanting more. I also felt that GM had fallen short on a few things. The MultiPro tailgate was seen as a service advisor’s nightmare every time someone left the ball on the hitch. The Dynamic Fuel Management fuel unfinished. If you’re like me, you remember Cadillac’s V8-6-4 system and you start comparing the two. Needless to say that GM's Active Fuel Management is a much better cylinder deactivation system overall.

Of course, the automotive media formed a chorus over GM's interior design for their full-sized half-ton pickup trucks. We were expecting a revolutionary design to match its bold exterior. Instead, we exited our pickup trucks disappointed. Unfortunately, I was one of those in the automotive media corps that felt that way.

Then again, we're not truck consumers primarily. Nor are most of us experts. However, I love pickup trucks. There is a sense of duty when driving one. That is what I expect out of each pickup truck that I work with.

2020 GMC Sierra 2500HD 4WD Crew Cab AT4

Following up on the half-ton GMC, a 2020 Sierra 2500HD arrived for me to work with. Again, it was the AT4 trim. On the larger frame with greater capacity and capability, I wanted to see whether they took a different approach to their Heavy Duty pickups for this new generation model.

Before I dive further into the truck itself, I wanted to explain GMC's approach to an off-road capable pickup truck. The AT4 designation replaces the All Terrain trim level. The focus is not just on appearance, but of enhanced capability – especially on its pickup trucks. On the Sierra 2500HD AT4, GMC adds Rancho shocks and an uprated suspension system, along with skid plates and all-terrain tires.

The Sierra 2500HD AT4 is not a unique offering, but a necessary one considering the growth in leisure customers in the full-sized truck category. For heavy-duty pickup buyers, they can choose from the Ram 2500 Heavy Duty Power Wagon and the new Ford F-Series Super Duty Tremor. It worth noting that GMC's AT4 and Ford's Tremor models are available on both the three-quarter-ton and the one-ton models, as well.

With that said, I still have to put GMC’s new heavy-duty pickup truck through my evaluation process.   

2020 GMC Sierra 2500HD 4WD Crew Cab AT4

I’ll start with what’s underneath the hood – the big 6.6-liter Duramax turbocharged V8 diesel. With 910 pound-feet of torque, it has more than enough low-end power to handle any condition. I love the strong response from the throttle, even with that signature diesel sound. Believe me, this heavy-duty Sierra is no slouch with the Duramax underneath the hood.

Attached to the big Duramax is an Allison 10-speed automatic transmission matched to provide smooth shifts. The four-wheel-drive system has a two-speed transfer case, which can be switched with a series of buttons on the left side of the instrument panel. You can also set it in an automatic mode if you wish.

When it comes to hauling, this Sierra 2500HD AT4 can tow up to 18,500 pounds – no matter if it is towed by a conventional hitch, a fifth-wheel, or gooseneck connection. The maximum payload is a hefty 3,862 pounds. These numbers are available when you choose the Duramax over the new gasoline-fueled 6.6-liter V8.


In terms of fuel economy – which really does matter to truck consumers – I averaged 17.4 MPG. For a heavy-duty diesel pickup truck, this is a very good fuel consumption average!

Considering my experience with the Chevrolet Colorado ZR2 Bison, I will always consider choosing a diesel engine if I have to do anything that does not involve a paved surface. That is, as long as I can fit this big truck on that so-called beaten path.

And, yes, it is a big truck. My Crew Cab tester has a six-foot-nine-inch box behind it. That stretches the truck over 250 inches in length. It also stands at 79.82 inches tall and sits at 81.82 inches wide – without measuring the mirrors. And, those mirrors can be set further apart from the cab for maximum towing vision by a press of a button.

2020 GMC Sierra 2500HD Crew Cab 4WD AT4

In other words, it is not a nimble pickup truck. Then again, you do not buy a heavy-duty pickup if you live in a condominium or a loft somewhere in the center of the city. And, don’t expect to use it at your local supermarket without having to take over two parking spots. You can, but…

What it does is to create a higher level of load management and access to setting up that load in the box. This AT4 tester comes with the MultiPro tailgate – a versatile piece of innovation. There are six ways to use this tailgate. To me, the best way to use this tailgate is when you can set it up as a step into the bed. A push of a couple of buttons will let you walk up into the box without worrying about bending any flimsy piece of metal. However, the steps have a load limit of 365 pounds. Luckily, I’m much lighter these days…

There is one small issue. If you tow a lot and forget to remove the ball from the hitch, deploying the steps on the MultiPro tailgate could (try, will) damage the exterior piece underneath the lower step. So, be a responsible truck owner and remove that ball from the hitch before you deploy the steps, please?

2020 GMC Sierra 2500HD Crew Cab 4WD AT4

Stepping inside the AT4’s Crew Cab, I know that this latest round of GM’s full-size pickups got a rap on their interior design. The chorus – myself, included – saw more evolution and lack of change over the previous generation. We even went so far to knock some of the functionality of the instrument panel and the switchgear.

For one, I found little differentiation between the half-ton and heavy-duty models in terms of the instrument panel. Yet, having previous experience in the newest generation of GM trucks, I was more familiar with the driver’s functions to have a more educated and experienced opinion this time around.

The four-wheel-drive system switches are easier to get to – if it means a bit of a stretch from a further seating position. Other switches appear to be more logical – such as the fog lamp button above the light control knob. All other controls are definitely logical and quality made.

2020 GMC Sierra 2500HD Crew Cab 4WD AT4

On the other hand, I wished that the instrument binnacle was better. Yes, the screens do help – as does the wide head-up display. In fact, the head-up display is the saving grace for my driving competency of this big pickup truck.

GMC offers the newest corporate infotainment system, which is much better than before. Despite some glitches on Bluetooth connectivity, the ease of setting up presets and the use of smartphone connectivity suites – in my case, Apple CarPlay – have improved greatly. One must not forget about OnStar and its usefulness on GM's vehicles. I would choose this over all other telematics systems across the industry.

Seating is solid, but a bit firm for me. I don’t mind, really, as it does adjust to you after a while. I have more than enough support in the AT4's front seats and can rudder this big truck the best that I can. Rear seat passengers will think they've gone to heaven with the mass of leg and headroom. Plus, there are a pair of small secret storage places behind the cushions for items that could be hidden away.

2020 GMC Sierra 2500HD 4WD Crew Cab AT4

There is a lot to be said about heavy-duty pickup trucks and their ability to drive through anything. AT4 owners will appreciate the smooth ride coupled with plenty of absorption over rougher patches of roadway. Handling is controlled for a large pickup truck, but evasive maneuvers will take more care to execute, Remember, this is a large truck to get around even tight obstacles.

Luckily, the steering system is responsive. Do not expect a tight turning radius, yet it can get you out of some tight situations rather precisely. I love that there is nominal play when the truck is on-center. As for the brakes – I love them! Probably the best in its class so far. The pedal feel is strong and the response to the rotors is superb.

When we talk off-road capability, we must address the obvious – tires. What will make the difference in using the Sierra 2500HD AT4 in the deep woods is to equip it with knobbier tires – BFGoodrich All Terrain KO2s, for example. These Goodyear Wranglers may be fine for highway and gravel road use, but I would need something with grip in mud and snow. This is just my opinion, folks…

2020 GMC Sierra 2500HD 4WD Crew Cab AT4

As far as pricing is concerned, the 2020 Sierra Heavy Duty pickup line starts at $35,600 for a base regular cab model with two-wheel-drive. Choosing the AT4 trim will jump the base price up to $57,700. That will require adding four-wheel-drive and switching to the Crew Cab. My tester came with a sticker price of $76,960.

I always have to take to heart my thoughts and feedback whenever I work with a pickup truck of its stature and importance. I truly have to bow down to those who use these trucks as intended. When I evaluate heavy-duty pickup trucks, I take them on a mix of conditions that I often see them used. If you must work with a heavy-duty pickup truck, not every one of these rigs are not going to be friendly in urban enclaves for non-work use. The caveat being "non-work," as in taking one to a concert or sporting event downtown. If you master these trucks in those situations, more power to you!

My roommate said it best that she would think that the heavy-duty pickup truck is better suited in places, like North Dakota. She can say that because she is from North Dakota. And, no, I did not take it into North Dakota to find out.

2020 GMC Sierra 2500HD 4WD Crew Cab AT4

Luckily, you do not have to go far from the Twin Cities to experience where these big trucks thrive. Farm communities are full of heavy-duty pickup trucks. I can definitely see plenty of new GMC Sierra Heavy Duty models out in these areas. Will some of them be the AT4 model? Probably. It is a great package that will make rural highways a breeze to navigate, as well as turning onto a gravel road onto the fields – or into the woods.

The new Sierra Heavy Duty is a great pickup truck to do the heavy work – towing horse trailers, bales of hay, fifth-wheel glamping, race cars, and so forth. The AT4 adds a new dimension to this newest of big trucks that adds more fun off the beaten tarmac. In all, yes, the GMC Sierra Heavy Duty AT4 is a fun pickup to own, when your needs call for an off-road capable heavy hauling rig.

DISCLAIMER: Vehicle provided by General Motors

All Photos by Randy Stern

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