The 2020 GMC Sierra HD 3500 AT4 is the massive off-roading version of the Sierra built to compete with other massive trucks such as the Ford Raptor and Ram Rebel. While the base model for the Sierra is pretty average, let’s see how the  HD 3500 AT4 compares. 

Is the GMC Sierra HD 3500 AT4 An Off-Roading Beast? 

The GMC Sierra HD 3500 AT4 starts around $57k, making it a more expensive option than the Ram Rebel that starts around $44k and more expensive than the Ford Raptor that starts around $53k. 

Power 

With this extra cost, you gain superior towing capabilities. The GMC Sierra 3500 HD AT4 can tow up to 21,300 lb. This blows the Raptor’s ability to tow up to 8,000 lb and the Rebel’s ability to tow up to 7,520 lb out of the water. 

The Sierra can tow more than double the weight of its competitors, and we do find that to be pretty beastly. 

This GMC truck is also incredibly powerful. It’s 6.6 liter V8 engine produces 445 horsepower and 910 lb-torque. However, the Ford Raptor produces 450 HP and 510 lb-ft torque. 

Drivers love this massive GMC’s ability to accelerate quickly. Despite its size, it can still hit 60 mph in only 19.8 seconds while hauling an 18,000 lb trailer. 

Off-Roading Specs 

The 3500 HD AT4 sits high with a ground clearance of 11.18”. The Raptor has a ground clearance of 9.4,” and the Rebel has a ground clearance of 8.1”. If being the tallest matters, then the Sierra wins. This Sierra model sits upon massive 20” tires as well. 

The 3500 HD AT4 also has an approach angle of 27 degrees when the Raptor has an approach angle of 30 degrees, and the Rebel has an approach angle of 29.3 degrees. 

While the Raptor has Fox Shox, the 3500 HD AT4 has twin-tube Rancho shocks along with an Eaton locking rear differential for a smooth, comfortable ride. The Sierra also comes with all-terrain tires and a skid plate to protect the undercarriage. 

The Sierra’s Traction Select System allows you to quickly select between different driving modes with varying configurations of traction to match changing terrains. For example, there is an Off-Road mode and a Tow/Haul mode. 

The Ford Raptor has a bit more off-roading tech with features such as Hill Descent control and more off-roading driving modes, including one for rock crawling and the Baja mode for driving in the desert. 

But the Sierra does have a Variable Steering Assist mode that helps you at low speeds by returning the steering to the center. It adapts to crowned road surfaces to make it easier to correct your steering on uneven surfaces, especially while hauling a more massive load. 

Yes, The GMC Sierra HD AT4 Is An Off-Roading Beast 

The GMC Sierra HD AT4 is an off-roading beast. It can certainly go down country roads and over adverse terrain without any issue. However, it’s meant for hauling items over these trails. If you need to pull something that weighs over 8,000 pounds, then this truck is for you. 

However, as far as off-roading goes, the Ford Raptor leaves competitors in the dust with the ability to crawl over rocks and race across the desert with ease.