Review: 2020 GMC Sierra 1500 AT4

Going out into the wilderness has always been a popular activity. With recent events, it has become even more popular so much so that auto manufacturers are offering off-road ready models of their popular vehicles. The latest to receive the off-road treatment is the 2020 GMC Sierra 1500 AT4.

2020 GMC Sierra AT4


Engine – The GMC Sierra 1500 is available with a number of engines. There’s a base 4.3L V6, a 2.7L Turbo, a 5.3L V8, a 6.2L V8 and what this particular demo vehicle has; a Duramax 3.0L Inline-6 turbo-diesel. This turbo-diesel engine produces 277 hp and 460 lb-ft of torque. Compared to the 3.0L EcoDiesel in the Ram 1500, this Duramax diesel engine feels a bit more responsive, as in, I didn’t have to press the throttle pedal quite as far as I did in the Ram to get the truck moving. This may also have to do with the 10-speed transmission and the fact that the Sierra is lighter. Of course if you want the most responsive engine then one of the gasoline V8 options are the ones to go for. But back to this inline-6, it is a smooth and quiet engine. Peak torque is reached at a very low 1,500 rpms. But the reason why one would consider a diesel engine is for fuel savings.

With this Duramax turbo-diesel engine, the 2020 GMC Sierra 1500 AT4 is rated at 9.2 L/100km (25.6 MPG) on a highway and 10.6 L/100km (22.2 MPG) in a city. Compared to the Ram 1500, the Sierra can achieve better city fuel economy but worse highway fuel economy. During my drive with the truck, I only averaged 11.5 L /100km (20.5 MPG) but that’s not the truck’s fault. I used remote start quite often in the mornings and I left the engine running while taking photos and video of it for the video review.

2020 GMC Sierra AT4

Transmission – The diesel engine is paired with a 10-speed automatic transmission. This is the same 10-speed automatic that GM co-developed with Ford. But while they both developed the hardware, the software is GM’s own and that makes a big difference. In normal driving situations, it’s extremely hard to perceive shifts as they are very smooth and quick. Realistically you can only tell that the transmission changed gears by hearing the rpms drop. If you put the Sierra in Tow/Haul mode, the CPU holds each gear for a longer period of time and engages the exhaust brake when slowing down.

Braking – The new generation 2020 GMC Sierra 1500 comes standard with 4-piston fixed calipers (like you would get on a sports car) and they provide a firm & strong brake pedal feel. When unloaded, it doesn’t take much brake pedal force to bring the Sierra 1500 to a stop from a substantial speed. Unfortunately emergency automatic braking is not standard but it is part of the Driver Alert Package 2 for $1,260 CAD ($1,095 USD).

2020 GMC Sierra AT4

Handling – The new generation Sierra is about 160 kg (360 lbs) lighter than the older model thanks to a redesigned frame, which is also stronger, and use of aluminum in the doors and bed. Paired with the new 10-speed automatic, the Sierra 1500 feels more agile than its predecessor. By no means is this a “sports truck” but it is more responsive when taking off from a stop or going around a corner. 

If you find yourself off the beaten path, the Sierra AT4 can tackle some light off-roading. It receives a factory 2-inch lift kit, a 2-speed transfer case, Rancho dampers, red recovery hooks, Traction Select Off-road mode, and skid plates. It also has an automatic locking rear differential but it has to detect wheel slippage first before it locks up and you can’t override it to manually lock it. 

2020 GMC Sierra AT4

Capability – As this particular truck is equipped, it can tow 9,000 lbs and has a max payload of just over 1,600 lbs. There is a sticker on the driver’s side door jamb that tells the driver exactly what tow, payload, GVWR, etc, ratings are for each specific truck. Of course those numbers will vary depending on cab & bed sizes, 2WD or 4WD, equipment and so on. So having that sticker and knowing exactly what your specific truck is capable of is a huge benefit when trailering or loading up the bed.

As for the bed itself, it is deeper and wider than the previous generation Sierra 1500. It has 12 fixed tie down points (3 in each corner) and each corner can handle up to 500 lbs of weight tied to it. LED bed lighting is provided next to the tailgate and an optional 120-Volt power outlet is available. This particular demo truck has the CarbonPro bed which is a carbon fiber composite bed that GMC claims is tougher than the standard steel bed. Also the CarbonPro bed is 60 lbs lighter than the steel bed and is corrosive resistant. 

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2020 GMC Sierra AT4


Ride Comfort – For the most part the 2020 GMC Sierra 1500 AT4 is a comfortable truck… for being a truck. Pickup truck suspension is generally set up to handle payload and towing weights which can make the ride feel stiff when it’s unloaded. But while this particular Sierra doesn’t have air suspension like the Ram 1500 or adaptive suspension like it’s Denali 1500 brother, it still manages to provide a relatively smooth and comfortable ride. It’s only when you encounter a very rough road that the ride becomes choppy and bouncy at times.

2020 GMC Sierra AT4

Interior Space – This crew cab GMC Sierra is larger than before with most of the extra space going to the rear occupants. 3-inches of extra legroom was added to the rear seats which makes for a lot of space in the rear seats, even for someone as tall as myself at 6’4”. Those rear seats can also fold up to allow for tall item storage and there are little “hidden” cubbies in the outboard seat backs. Front occupants also have a lot of space with plenty of adjustability in the seats and steering wheel. There are also plenty of places in the cabin for you to lose items… I mean store items. There are 2 glove boxes, the center console is massive, there are deep door pockets, and a large tray-like spot for smartphone wireless charging just in front of the center console.

Noise, Vibration, & Harshness – When driving on city streets, the cabin of the SIerra AT4 is well insulated from outside and engine noises. It’s when you get onto a highway does the cabin start to get loud. The engine is very audible when accelerating and the Goodyear Wrangler Duratrac off-road tires are very loud at high speeds. 

2020 GMC Sierra AT4

Odds and Ends

Gadgets – The most unique feature to the AT4 is the MultiPro tailgate. It has 6 different functions which range from a small workbench to a step for easier bed access. It comes standard on the AT4 trim along with the SLT and Denali trims of the GMC Sierra. This tailgate is much more useful than Ram’s barn door tailgate but just be aware when dropping the inner gate if you have a tow hitch bar as it will hit.

Other gadgets in the 2020 GMC Sierra 1500 AT4 include a rear camera mirror which provides an unobstructed view behind the truck, surround view cameras which are a tad on the laggy side at night but are high resolution in the daytime, heated and ventilated front seats, heated rear seats, and a 15-inch head-up display. A panoramic sunroof and a larger infotainment screen like in the Ram 1500 would be nice additions but sadly they’re not available in the Sierra. 

2020 GMC Sierra AT4

Interior Design – While this new generation GMC Sierra has an updated interior look over the previous generation, it’s not on the same par as the Ram 1500’s interior. The interior of the Sierra looks utilitarian and not like a product of 2020. Remove the touchscreen and it looks like it’s straight from 2002. But the large buttons and knobs makes it very easy to adjust the climate control or turn different functions on or off even with thick gloves on during the winter. Hopefully the 2022 interior update will make it look more modern.

Exterior Design – The exterior looks more fresh than the interior. LED headlights are standard across the Sierra lineup along with LED daytime running lights. This AT4 trim looks a bit more off-road ready with the taller ride height and the chunky tires. The rear bumper retains the corner steps which are now bigger to accommodate large steel toe boots. Overall exterior dimensions have increased in width, height, and length and somewhat makes the new Sierra 1500 look more like a 2500 or 3500 truck.

The 2020 GMC Sierra 1500 AT4 in crew cab, short bed 4×4 configuration starts at $63,098 CAD ($56,290 USD). Loaded up like this demo truck, you’re looking at closer to $75,000 CAD ($62,330 USD). While the GMC Sierra is a great truck for carrying things in the bed and comes well equipped to handle light off-roading, the Ram 1500 Rebel would be my choice. The Ram has a nicer interior and with the air suspension, it provides a better overall ride. The Ram does have a smaller bed so if you need to use the bed often, the Sierra should be your choice. But most customers use their trucks as an SUV for transporting their family and groceries more often than as a truck and the Ram does that job better. Hopefully with the mid-cycle update, GMC will give the Sierra the air ride suspension of the new Yukon. Then it will be a much closer competition between the Sierra & Ram.

Thank you to GMC Canada for providing the vehicle.

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