Whether you need a heavy-duty pickup truck for the towing capacity, a light-duty truck for hauling, or an off-road-ready SUV, you'll find GMC is shaking things up with their 2020 lineup. With a full redesign to the 2020 Sierra HD, important updates to the 2020 GMC Sierra light-duty and an all-new AT4 trim for the 2020 Acadia, GMC combines innovative technology with rugged capability across their lineup. Of course, we couldn't just take GMC's word for it, so we traveled out to Jackson, Wyoming to drive the freshly updated vehicles. It wasn't all fun and games, however. We also put the trucks to work by testing their towing and payload capacities with some heavy trailering and hauling. Learn what makes these vehicles 'bigger, stronger and smarter' than ever before.

2020 GMC Sierra 2500 HD  

Sierra AT4 HD Towing
Towing a 14,000-pound box trailer was no problem for the 2020 GMC Sierra HD.

For 2020, GMC outfits the Sierra HD with all-new architecture, styling that is unmistakably "heavy-duty", increased towing and hauling power, a truckload of tech, and a first-ever AT4 trim. When we arrived in Jackson Hole, Wyoming, we wasted no time trying out the new Sierra HD. We were greeted by the 2020 GMC Sierra HD Denali waiting for us with a large trailer hitched. Our first impression was the commanding exterior styling of the heavy-duty truck. As GMC put it "HD customers really don't want to look like they are driving a light-duty truck." Answering this plea, GMC's design team made nearly every part of the Sierra HD taller, wider and more aggressive.

Exterior Features

2019 Sierra HD Denali Styling

To create a heavy-duty truck that is more authoritative on the road, the Sierra HD gets a longer wheelbase, taller hood line, and a large, attention-grabbing front grille. Above the grille sits a hood scoop that has function, in addition to form, providing an advanced cooling system for the Sierra's Duramax turbo diesel engine. Despite the truck's increased height, the bed becomes more user-friendly thanks to a one-inch lower lift in height for easier loading and trailer hitching.

GM Multipro tailgate
GMC's MultiPro tailgate is standard on the Denali and AT4 trims for easy loading. 

GMC's MultiPro tailgate is available on all trims of the Sierra heavy-duty and it comes standard on the Denali and AT4 trims we drove. It offers 6 configurations to help with loading and unloading cargo. New for 2020, the Sierra HD also gets cargo bedside steps for even more convenience. A Bluetooth speaker system built into the tailgate can be used for those who like to whistle while they work or those who like to celebrate after a job well done. 

Interior Features

GMC Sierra HD Denali

The interior of the 2020 Sierra Denali HD offers best-in-class front legroom and headroom and it welcomed us with an airy front row and spacious rear seats. Our Denali trim was packed with premium materials like pebbled-grain leather seats and real open-pore wood trim that gives the truck a sophisticated and luxurious feel. The interior offered plentiful storage space, wireless phone charging and an easy to use infotainment system that connects with features like the first-in-class head-up display that can be pre-set for trailering information, speed, navigation and an inclinometer display for the road grade. We found having the navigation on the head-up display to be especially helpful for keeping our eyes on the road instead of looking down at the infotainment screen or our phone. 

Our first task was to take out a Sierra HD Denali with a camper weighing in at 11,000 pounds hitched. Having never towed that much weight before, we were eager to learn about the trailering technology that was going to help us get to our destination safely.  


Invisible trailer
The transparent trailer camera view lets the driver see right through the trailer. 

GMC's ProGrade trailering system in the GMC Sierra HD offers safety features like 15 unique camera views including a first-ever transparent trailer view which we found to be the most useful during our trailering experience. This feature allows you to see through the trailer using cameras on the truck's tailgate and mounted on the trailer. 

New for 2020, is GMC's Smart Trailer technology which gives owners the ability to control features like turning on the trailer’s air conditioning or water heater, and monitoring fuel levels through a central iN∙Command control system which can be accessed from a phone app or the truck's infotainment system. 

Powertrain and Towing 

2020 GMC Sierra HD Towing

According to GMC, the #1 reason for the purchase of a Sierra HD is towing. 93% of HD customers use their trucks for towing and 50% tow more than 8000 pounds. These stats stayed top of mind for the redesign of the 2020 Sierra HD, starting with updated powertrains for increased towing and payload capacity. The Sierra HD's 6.6L Duramax turbo-diesel offers 445 horsepower and 910 lb-ft of torque and gets mated to a segment-first Allison 10-speed automatic transmission. After all the updates, the Sierra HD gets a max towing capacity of 35,500 pounds which is a healthy increase of 52% from the last generation. An all-new 6.6L V8 gas engine is also available for 401 hp and 464 lb-ft of torque.

Our first trailering route took us on the highways of Wyoming with 11,000 pounds following behind our Sierra Denali HD. Although new to trailering, we gained confidence in the process as we used the truck's towing technology and tow mode. Pulling the large trailer did make it more difficult to accelerate at times and we sensed some shakiness on fairly smooth roads.

When we switched out the large camper for a more compact (though heavier) box trailer weighing in at 14,000 pounds the following day, we realized how wind resistance can impact the driving experience. Due to the smaller size of the trailer, many of the concerns we experience with the camper were eliminated. The capable powertrain and transparent trailer view in the trailering system gave us newfound confidence in our towing skills. 

Hauling in the 2020 GMC Sierra AT4 HD

GMC Sierra AT4

Launched last year on the GMC Sierra light-duty trucks, the AT4 trim brings a new level of adventure to GMC's lineup, and for 2020 it is available on the heavy-duty lineup. From the exterior, you'll immediately recognize the AT4 thanks to dark chrome finishes, front and rear bumpers, and a body color grille surround. The interior also gets the AT4 treatment with an athletic appearance, dark leather-appointed seats with AT4 badging on the headrests and all-weather floor liners ready to take on the mud brought in from the off-road jaunt. 

The beauty of the Sierra AT4 HD is far from only skin deep. It also gets new features to help it leave the pavement including off-road suspension, Rancho shocks, skid plates, Eaton locking rear differential, eighteen-inch wheels wrapped with Michelin all-terrain tires, and a Traction Select System with specific Off-Road mode.


payload capacity ram vs. GMC
The Sierra HD AT4 hauls up to 3,615 pounds which is almost double that of the Ram 2500. 

On the second day of our trip, we drove the 2020 Sierra HD AT4 with two thousand pounds of logs in the bed. We then took the truck, along with our cargo, off-pavement to see how it handles a dirt road along with the weight. The max payload of the Sierra HD AT4 is 3,615 pounds (nearly double that of the Ram 2500 as demonstrated by the piles of logs above). This meant our load was no concern for the capable Sierra HD AT4. We found the truck's ride stayed smooth on paved roads and handled the off-road path without giving us any trouble with acceleration or braking. 

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2020 GMC Sierra 1500 LD  

GMC Sierra Light Duty

The big spotlight may have been on the redesigned 2020 Sierra HD Denali and AT4, but the Sierra 1500 also got some key updates for 2020. The light-duty also gets the multi-color head up display, rear camera mirror and a first ever CarbonPro box which GMC claimed is virtually indestructible and then gave us heavy objects to throw inside (we barely scuffed it). 

The light-duty also gets a new engine in the form of a 3.0-liter Duramax turbo diesel making the Sierra 1500 the most efficient Sierra truck yet with up to 30 MPG highway. The torque goes up to 460 lb-ft and it scores a best in class 277 horsepower. The light-duty can tow a maximum of 9,100 pounds and has a payload of 1,830 pounds.

GMC Sierra AT4 LD

Like its heavy-duty sibling, the 2020 Sierra 1500 AT4 maintains its off-road prowess which we got to test out going through some tough terrain that GMC set up to demonstrate its capability. This included a rock hill, mud, and steep hill inclines. The AT4 made it through the course easily thanks to its long list of off-road features. 

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2020 GMC Acadia AT4 

2020 GMC Acadia AT4

After completing our test drives in the light-duty and heavy-duty trucks, GMC let us get our hands on the all-new 2020 Acadia AT4 for a quick spin around town. The redesigned 7-seater SUV gets a bolder exterior with a new front and rear fascia, new wheel options and the first-ever AT4 trim with a 3.6L V6 engine for 310 horsepower and 271 lb-ft of torque. The AT4 trim adds exclusive interior and exterior finishes, an advanced twin-Clutch AWD system and all-terrain tires for optimal off-road capability. 

2020 GMC Acadia

Safety features like the Head-Up Display, Lane Change Alert with Side Blind Zone Alert, Rear Cross Traffic Alert & Rear Park Assist, along with the upgraded suspension made our ride around town worry-free, quiet and enjoyable. The interior of the Acadia AT4 impressed us with comfortable leather seats sporting the AT4 badge on the headrest proudly announcing the arrival of this athletic trim to GMC's popular SUV. Although we didn't get the chance to take it off the pavement, the street drive in the 2020 Acadia was a great way to wrap up our scenic road trip around the mountain-lined roads of Wyoming in GMC's capable and luxurious lineup. 

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