2020 GMC Sierra 2500 AT4 Crew Cab

2020 GMC Sierra 2500 AT4 Crew Cab in Summit White

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2020 GMC Sierra 2500 AT4 Crew Cab

Class: Large Pickup Truck

Miles driven: 209

Fuel used: 15.3 gallons

CG Report Card
Room and ComfortA
Power and PerformanceB+
Fit and FinishB
Fuel EconomyD+
Report-card grades are derived from a consensus of test-driver evaluations. All grades are versus other vehicles in the same class. Value grade is for specific trim level evaluated, and may not reflect Consumer Guide's impressions of the entire model lineup.
Big & Tall Comfort
Big GuyA
Tall GuyA
Big & Tall comfort ratings are for front seats only. "Big" rating based on male tester weighing approximately 350 pounds, "Tall" rating based on 6'6"-tall male tester.
Engine Specs445-hp 6.6-liter
Engine TypeTurbodiesel V8
Transmission 10-speed automatic
Drive Wheels4WD

Real-world fuel economy: 13.6 mpg

Driving mix: 75% city, 35% highway

EPA-estimated fuel economy: NA

Fuel type: Diesel

Base price: $57,700 (not including $1595 destination charge)

Options on test vehicle: Duramax 6.6-liter V8 turbodiesel ($9890), AT4 Premium Package ($4215), Technology Package ($2125), power sunroof ($995), Driver Alert Package II ($645), gooseneck/fifth-wheel package ($545) AT4 Premium Package discount (-$750)

Price as tested: $76,960


Quick Hits

The great: Extra-large cabin; power of Duramax diesel engine

The good: Long list of comfort, convenience, and driver-aid technology features

The not so good: Fuel economy, steep pricing; gigantic dimensions make close-quarters maneuvering and parking a chore

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CG Says:

It’s a testament to modern vehicle engineering that heavy-duty pickup trucks—beasts of burden that used to be used solely for hard work and heavy hauling—have become comfortable and refined enough to use for daily commuting. And in recent years, they’ve been getting more and more luxurious too.  Case in point: the 2020 GMC Sierra 2500 AT4.

2020 GMC Sierra 2500 AT4 Crew Cab

Standard features on the Sierra 2500 AT4 include GMC’s configurable MultiPro tailgate (see the gallery below for pictures of the open tailgate), side bedsteps, and GM’s CornerStep rear bumper.

AT4 is GMC’s recently launched “premium off-road” sub-brand. Technically, AT4s aren’t the most luxurious steeds in GMC’s stable—that honor goes to the top-of-the-line Denalis—but they are the penultimate models, and most of them receive a host of off-road and upscale features. The AT4 nameplate has quickly proliferated across GMC’s model lineup. The brand was introduced on the redesigned Sierra 1500 as a mid-2019 addition and was followed by the Sierra 2500 and Acadia midsize SUV for 2020. For 2021, the Canyon compact pickup, Terrain compact SUV, and redesigned Yukon large SUV join in.

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2020 GMC Sierra 2500 AT4 Crew Cab

The AT4 Premium Package brings long list of equipment, including a premium infotainment system with navigation, Apple CarPlay and Android Auto functionality, and a Bose premium sound system.

The AT4 trim level isn’t the only thing that’s new for the Sierra 2500 for 2020; GM’s heavy-duty pickups were redesigned as early-2020 models, following close on the heels of their half-ton kin, which were redesigned for 2019. The AT4 trim level gives the Sierra 2500 all-terrain tires, off-road suspension with Rancho-brand shocks, locking rear differential, underbody skid plates, MultiPro multi-function tailgate, and the ProGrade Trailering System (which offers 15 different camera views) as standard equipment. Distinctive appearance signatures include blacked-out grille and body trim, bright-red tow hooks, and a Jet Black leather interior with caramel-colored “Kalahari” accents.

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2020 GMC Sierra 2500 AT4 Crew Cab

All GMC AT4 models have Jet Black leather upholstery with caramel-colored “Kalahari” inserts. The Sierra 2500’s console-bin cover includes a smartphone-sized depression with a “grippy” surface, and the AT4 Premium Package adds a wireless charging pad in the bin forward of the dual cup holders.

The $57,700 base price of our test vehicle also brought standard amenities such as heated/ventilated front seats and heated outboard rear seats, heated leather-wrapped steering wheel, and heated power folding-extending trailering mirrors with auto-dim.

The king of the options list is the 6.6-liter Duramax turbodiesel V8—it puts out 445 horsepower and a whopping 910 lb-ft of torque, and adds a cool $9890 to the bottom line. That steep price tag is not unusual—the available turbodiesel V8s in HD pickups all hover around the $9K mark. The Duramax’s maximum towing capacity—18,500 pounds—isn’t quite at the level of its Ford F-250 and Ram 2500 rivals, and the engine noise will remind you you’re driving a diesel. However, the alert 10-speed transmission shifts smoothly, and acceleration—at least when unladen by a trailer or heavy cargo—is surprisingly robust for such a large truck.

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Front-fender badges announced the presence of the big-ticket item on our test vehicle’s option list. The 6.6-liter Duramax turbodiesel V8 puts out 445 horsepower and 910 pound-feet of torque.

And when we say large, we mean it: The 2500s are about 10 inches longer overall than their 1500 kin, which are hardly svelte vehicles to start with. Our standard-bed test pickup was six and a half feet tall and almost 21 feet long. Plus, the extra-tall ride height/seating position and the blocky front-end styling means that all-around visibility can be a challenge.

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Sierra AT4 Wheels

The Sierra 2500’s extra tall ride height and body build are apparent from the side view. Twenty-inch machined-aluminum wheels are included in the AT4 Premium Package, as are black running-board assist steps.

Key features of the $4215 AT4 Premium Package are front and rear park assist, lane-change alert with side blind-zone alert, rear cross-traffic alert, and a set of “big-rig”-style LED roof marker lamps. The $2125 Technology Package includes a HD Surround Vision, rear-camera mirror, bed view camera, and a multi-color head-up display (this handy feature delivers a wealth of information, including lane-departure-warning and forward-collision-warning readouts and inclinometer displays that show fore-and-aft  and side-to-side tilt when off-roading). The $645 Driver Alert Package II adds forward collision alert, lane departure warning, automatic emergency braking, automatic high-beam headlights, a following distance indicator, and GM’s Safety Alert seat (which vibrates to warn of potential hazards). Though it’s a bummer you’ll have to fork over almost $7000 extra to get all those features, they make the Sierra 2500 a little easier to handle in suburban driving.

High step-in is helped by the standard running boards and door-pillar-mounted grab handles, but you’ll still need to hoist yourself up into the Sierra’s cab. Once you’re there, you’ll find a pleasant interior with some upscale touches, but the overall ambiance here doesn’t match comparable Ram 2500 or Ford F-250 models.

The EPA doesn’t test heavy-duty pickups, so there are no official fuel-economy estimates. Not surprisingly, big trucks that offer this kind of towing and hauling power are thirsty vehicles. Our test consisted of mostly highway driving, but we couldn’t top 14 miles per gallon. That’s right on par with the most recent Ford F-250 Super Duty diesel we tested.

Heavy-duty pickups’ thirst for fuel and extra-large proportions should make average consumers think twice about whether they truly need THAT much towing and hauling capacity in their pickup truck. For those that do—and can foot the substantial bill—the GMC Sierra 2500 AT4 offers a respectable level of luxury and and a generous list of helpful available tech features.

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2020 GMC Sierra 2500 AT4 Gallery

2020 GMC Sierra 2500 AT4