1. home
  2. news
  3. features
  4. 2020 GMC Sierra 1500 AT4 3.0L Duramax: Tested Off-Road

2020 GMC Sierra 1500 AT4 3.0L Duramax: Tested Off-Road

Does AT4 really mean off-road package?

The 2020 GMC Sierra 1500 AT4 3.0L Duramax qualified for this year's test with the combination of the AT4 off-road package and the new 3.0L Duramax diesel engine. See how the Sierra half-ton survived our flogging in the 2020 Pickup Truck of the Year test.

What's Hot

  • 0L Duramax diesel + 10-speed automatic
  • Definitely won our fashion contest
  • Well-composed suspension

What's Not

  • We'd prefer a selectable locking differential
  • Low-hanging plastic

2020 GMC Sierra 1500 AT4 New Features

The 2020 GMC Sierra 1500 AT4 took a bit of engineering magic to fit the new powerplant under the hood, but GM's 3.0L inline-six Duramax diesel has finally met the Sierra 1500 AT4. The engine comes with a suite of tech including a lag-reducing variable-geometry turbocharger, a high- and low-pressure exhaust gas recirculation system to keep parasitic turbo boost losses (and emissions) to a minimum, a variable intake manifold, and active thermal management to keep the I-6 within its optimal temperature range. Next up for the 277 horses and 460 lb-ft of torque is the Hydro-Matic 10L80 10-speed with a habit of keeping the engine within its grunty powerband.

Sierra 1500 Articulation Scoring

The GMC Sierra 1500 AT4 had redesigned springs, which gave the truck a 2-inch lift and Rancho shocks to damp its motions, and it idled up the 22-degree RTI ramp to claim a score of 416, the highest score of all our independent-front-suspension-clad trucks and the second-highest score overall.

Speed Testing

The 2020 GMC Sierra 1500 AT4's 0 to 60 time of 8 seconds put it right in the middle of the truck lineup, and the same could be said about its 60 to 0 braking distance of 130.4 feet. Using its 3.0L Duramax diesel powerplant, the Sierra covered the quarter mile in 16.2 seconds hitting 85.9 mph.

Interior and Exterior

We witnessed many of the judges turning their heads and nodding in approval of the 2020 GMC Sierra 1500 AT4's looks. "It's surprising what a couple inches of lift and mean-lookin' tires can do for a half-ton," noted one judge, referencing the improvements in stance afforded by the AT4 package. Goodyear Wrangler DuraTrac tires on 18-inch wheels were nice on paper, but some of us wished the combo looked bigger in the wheelwells. Around back, sneakers and work boots alike found the bumper's molded steps useful for accessing cargo stored in the box, and one judge happily exclaimed, while surveying the CarbonPro bed and its 14 tie-down points, "It's got more hooks than I have fingers!" We also watched judges explore the six-function MultiPro tailgate and heard reviews of "campfire chair and cooking table all in one," and "I didn't know I needed this."

Stepping inside the Sierra 1500 AT4 garnered responses of "it's sleek and refined" and "not a lot of frilly doodads," while other judges just couldn't get on board with the feel of the interior. One judge commented, referencing the Sierra's spacious second row of seating, "I could sleep comfortably back here, on the floor!"

Pavement Performance

Pressing the 2020 GMC Sierra 1500 AT4's accelerator led one judge to comment that it had "just the right amount of diesel, all the good stuff, not the noise." Another wrote how they "desperately wanted to tow something with it." We found the I-6 and 10-speed to be a fun and sporty combo when we needed it to be while also logging the very respectable fuel economy numbers of 24.6 mpg. Judges gave a few thumbs in the upward direction to the feel of the brakes, the head-up display, and the cheery natural light afforded by the truck's sunroof.

GMC Sierra Off-Road

Judges were quick to comment on the two drastic changes to the 2020 GMC Sierra 1500 AT4. First, the Duramax diesel got their attention, as one of them wrote, "All the torque is right where I want it, especially when in 4-Lo." Goodyear DuraTrac tires got mainly high marks from the judges, especially when testing in the snow and on muddy trails. After putting traction control systems to the test, judges found them to be "present, but not too intrusive in the sand," while another judge, after a stint on a snowy backroad commented, "The nannies actually kept me safe!" When traveling at higher speeds over bumps and dealing with cantaloupe-sized rocks at low speed, we noticed changes (for the better) in the shock tuning, which kept the dreaded pogo effect at a minimum. With a suite of available camera views on the infotainment screen, one judge commented, "I can now wheel confidently solo with my little digital spotters!" Cresting over hills and inspecting the proximity of rocks to the sidewalls was suddenly a button push away. Though the plastic side steps helped with ingress, some judges wondered, "If AT4 is an off-road package, shouldn't these be rocksliders?"

Our Take: Does the AT4 Off-Road Package Hold up?

Yes, just please give us a selectable locking rear differential. Otherwise, the badging, skidplates, shocks, tires, and red tow hooks do a more than adequate job of keeping us happy in the absence of pavement. The suspension is tuned respectably well to handle jarring bumps and delivers far fewer bottom-outs than one might expect. Though not perfectly outfitted for high-horsepower dune-whomping, the Duramax diesel is grin-inducing on slow-speed obstacles. Off-road cameras (especially the forward-facing view, for spotting over the truck's nose) are your friend in the Sierra, and most (but not all) of us are itching for an updated interior.