2021 GMC Sierra 2500 HD 4WD Diesel Crew Cab AT4: A Stylish, Fuel-Efficient, Off-Road, Work Horse

Highlight: The Sierra HD AT4 is designed for cruising around town or conquering rough off-road terrains.

Test Vehicle’s MSRP: $78,050 (Base SE Model: $43,790)

Seating Capacity: 5

Standard Safety Features: airbags; ABS; an electronic stability control system; a teen driver safety mode mechanism; a trailer sway system; an Onstar safety and concierge system; LED side marker lights; LED fog lamps; LED cargo area lighting; front recovery hooks; and GMC multipro tailgate

Standard Equipment (AT4): 18-inch all-terrain tires; a two-speed automatic transfer case; an off-road tow-haul mode; a 220 amp alternator; 120-volt power outlet in cargo bed and instrument cluster; a heavy duty air cleaner; X31 off-road suspension with twin turbo Rancho shocks; skid plates; a digital variable steering assist system; a trailering package; a trailer brake controller; a pro grade trailering system; a remote start system; in-vehicle Wi-Fi; a keyless access system (all four doors); a push button ignition starter system; a dual zone climate control system; power front bucket seats; heated front and rear seats; ventilated front seats; 60/40 folding rear seat with a center armrest; a driver’s seat with memory control; a heated and leather wrapped steering wheel; premium floor liners; cornerstep rear bumpers; side bedsteps; 12-fixed cargo tie downs; power folding extended heated trailer mirrors; and a spray-on bedliner with AT4 logo

Optional Features On Test Vehicle: Turbo diesel; a bed view camera; a surround vision with two trailer camera provisions; universal home remote; a rear sliding power window; a premium infotainment system with a navigation system; an 8-inch touchscreen voice recognition; Bluetooth audio streaming; wireless Apple Carplay and wireless android auto; a Bose premium sound system; a wireless charging system; LED roof marker lamps; front and rear park assist; a lane change alert with side blind zone alert; a rear cross traffic alert system; a forward collision alert system; a lane departure warning system; an automatic emergency braking system; an automatic emergency braking system; intelligence automatic high beam; a following distance indicator; a safety alert seat; a power sunroof; a rear camera mirror; a heads up display system; a driver info center; AT4 high clearance step; 20-inch aluminum wheels; red tintcoat paint; gooseneck 5^th wheel; stamped bed holes with caps; a 7-pin trailer harness; and a rear axle 3.42 ratio

Other Trims:

2500 HD Reg Cab

2500 HD Double Cab

2500 HD Reg Cab

3500 HD Double Cab  

3500 HD Crew Cab                                                                                             

Standard Audio On Test Vehicle: AM/FM with Sirius

Apple CarPlay/Android Auto: Yes

Bluetooth Connectivity: Yes

USB Connectivity: Depending On Trim

Bumper-to-Bumper Warranty: 3 years or 36,000 miles

Powertrain Warranty: 5 years or 100,000 miles

Standard Engine/Horsepower: 6.6-liter, 8-cylinder/445-hp

Recommended Fuel: Diesel

Standard Fuel Mileage: no fuel economy info for 3/4 or 1 ton vehicles.

Base GVWR: 11,150

Maximum Payload: 3,563 lbs

Towing Capacity: 18,500 lbs

What’s New: For the 2021 model year, the Sierra HD is essentially a carryover model, after going through a redesign last year. A new enhanced camera for  trailering provides the following: jack-knife alerts, a bed view with zoom, hitch guidance and a rear side view with a trailer length indicator

Furthermore, wireless Apple CarPlay and Android Auto are now standard.

Why: With its bold premium exterior design, the GMC Sierra continues to be a standout in the fullsize truck segment, especially, when the truck is outfitted with an optional 6-stage tailgate. To remain competitive in the segment, some of the automakers have stepped up their game, adding their own version of a multi-level tailgate.

Ironically, GMC’s sibling, the Chevy Silverado does not offer this level of variations with its tailgate. However, we hear one is coming.  To add to that point, GM went to great lengths with their current generation of trucks to move beyond slapping different grilles on their fullsize trucks. This time around the design theme of both trucks goes skin deep. In fact, GMC’s trucks win hands down win judging the exterior styling. Numerous critics have taken Chevy’s design team to task over its controversial cat-eyed front headlights embedded in its grille.

GMC’s fullsize truck, which is available in a variety of cabs, beds and powertrains, is available in a multitude of trims too. The vehicle is available in either a 2WD or a 4WD configuration. The fullsize truck continues to serve many needs, ranging from being a basic work horse to a luxury cruiser that’s great for business meetings on the farm or five star vacations at the Ritz Carlton hotel.

The Sierra Crew Cab 2500 AT4 we reviewed was designed for off-roading. GMs 2500 HD trucks are available with either a single or dual rear wheel. Our 2500 HD truck was equipped with single rear wheels. 

The AT4 trim pushes the 4WD beyond the expected. It is designed for navigating rough terrains. The MultiPro tailgate provides up to 15 innovative camera views that are no longer aid in trailering, but for visibility on tight corners too. In fact, the suspension in the AT4 has been enhanced to include Rancho shocks, skid plates and a locking rear differential. Moreover, the Sierra AT4 is outfitted with such aids as a traction select system to a hill descent control to a surround vision HD camera for low-speed views of the truck’s surroundings.

Even more important, our test model was configured with a fairly quiet 6.6-liter turbo diesel engine. The workhorse engine is capable of spewing out effortlessly 445-horsepower. On a tank of fuel the vehicle is capable of traveling 487 miles. The Sierra 2500 HD 4WD we reviewed was also optioned out with a fifth wheel, enhancing the towing capabilities. Yes, this power house truck was engineered to pull upwards of 18,500 lbs, with the Durmax diesel.

Lastly, our Sierra 2500 HD CrewCab, with all of its luxury car amenities, was capable of comfortably seating five large adults, especially with the AT4 trim which was outfitted with leather perforated seats ventilated  (and heated) front seats. 

Yes, GMC has designed an all-weather truck that suitable for any lifestyle activity.

But: While all of the shine for GMC’s trucks is literally outside the vehicle, the interior wasn’t as fresh, modern and luxurious, as the exterior. The interior design team, as well as the entire fullsize truck segment should take a page from the current class-leading Ram 1500, with its iPad-like infotainment screen. The Ram interior design team has literally pushed the truck segment into stratosphere range, with its oversized, easy-to-use iPad-like touchscreen.

Another quirk of ours was related to the seats. They're just too firm. While trucks have become the replacement for sedans and coupes, its imperative that the seating comfort catches up to the exterior design. If the folks from Ram and Ford have gotten the formula right, so can General Motors.

Added to that the 4WD model requires additional endurance and flexibility to climb into the cabin.

And, without such optional driver assist features as a lane change alert system to a blindzone alert system, the Sierra 2500 4WD would be extremely difficult to navigate, while driving with other vehicles. These driver safety aids should be standard on all trucks. These feature will aid in the minimization of accidents.

Lastly, the price range of trucks have become out of reach for most consumers, as the price tag push closer to the six figure range. This has caused consumers to stretch out their payments -- into car mortgage territory. Our test model was just $2,000 shy for $80,000.

Verdict: Today’s trucks have become the new flagship vehicles as coupe, convertible, hatchback and sedan sales wane. Trucks have stepped up to the plate taking their market share by not only offering a roomy cabin, but the towing and pulling power the vehicles noted lack.

GMC’s Sierra trucks, which are available in a variety of engines, cabs and trims, are making every effort to make cars yesterdays news – even as the prices continue to reach record levels.  

Competition: Ford Super Duty F-250 Lariat and Ram 2500 HD Laramie Longhorn 4WD