Car Reviews

GMC updates the Sierra HD for 2020, including latest high-end Denali model

For 2020, the Sierra 2500 Denali is larger and bolder, the purpose-built exterior pairing functional design with exclusive style.

The next generation 2500 Sierra Denali. GMC/TNS

GMC’s Sierra 2500 HD (heavy duty) is a capable work truck with a heart of comfort and luxury.

The next generation 2500 Sierra Denali for 2020 comes in four-wheel-drive Crew Cab with a six-foot, nine-inch standard bed or an available eight-foot bed. Base price is $63,700 (plus $1,595 freight), with the longer bed adding $200.

For 2020, the Sierra 2500 Denali is larger and bolder, the purpose-built exterior pairing functional design with exclusive style.

New features include a Side Bed Step in front of the rear wheel arches, power-adjustable trailer-tow mirrors, a Bed View Camera (Denali Ultimate Package, $2,870), camera-based Adaptive Cruise Control and HD Surround Vision (Ultimate Package).

Side Bed Step complements the Corner Step rear bumper for easy access. Door-mounted, heated, chrome-capped trailer-tow mirrors fold, extend and retract at the touch of a button and feature auto-dimming upper glass, lower convex mirrors, LED turn signal/clearance lights, distinct front-facing vertical LED task lights and rear guidance lights (to enhance visibility when backing with a trailer.)


The Bed View Camera, integrated into the Center High Mount Stop Lamp provides an elevated view of the bed to assist with fifth-wheel or gooseneck hitching and to check cargo. Adaptive cruise maintains a set speed and also a set following distance from preceding traffic. Surround Vision uses cameras mounted in the front, rear and sides to provide clear views in all directions.

The Ultimate Package also brought a Rear Camera Mirror, multi-color 15-inch Head-Up Display and a power sunroof. Rear Camera Mirror projects a wide-angle image from a rear camera to the rear-view mirror.

My ruggedly handsome Sierra 2500 Denali was Carbon Black Metallic ($495) with signature multidimensional Denali grille featuring high-gloss mesh and chrome inserts, chrome vertical front recovery hooks, chrome six-inch assist steps and distinct 20-inch multidimensional polished aluminum wheels with all-terrain tires.

High-intensity LED headlights, signature C-shaped LED light-blade daytime running lights, LED taillights and fog lights are standard.

Power was provided by a 445-horsepower 6.6-liter Duramax Turbo-Diesel V-8 engine ($9,750), connected to an Allison 10-speed automatic transmission, producing up to 910 pound-feet of torque. Air drawn through the hood scoop and the large front grille by the dual-path Diesel Intake System provided cooler induction air to maximize horsepower and optimize trailering performance.


An exhaust brake restricted exhaust to create back pressure, retarding engine speed to offer supplemental braking — so effectively that it can slow a heavy vehicle on a downgrade without the use of mechanical brakes.

Tow/Haul mode offers better control and improved cooling when towing or hauling heavy loads and comes with a reminder to engage when a trailer is detected. Tow/Haul remains engaged up to four hours after turning off the engine.

Auto Grade Braking (active in Tow/Haul mode) automatically downshifts to enable engine braking on downhill grades, reducing brake wear.

Useful during my review week, engine block heating eased cold weather starts, heating block fluids as well. Engine After Run keeps the engine running for up to 15 minutes to allow cooling after a strenuous haul, using the fan and coolant.

An automatic-locking rear differential is standard and reacts in milliseconds in low traction to improve safety on slippery surfaces. My Sierra Denali had four-wheel drive with a two-speed Auto Trac transfer case. The Traction Select System with preset drive modes for different terrain/weather conditions adjusts shift points, throttle and Stabili Trak for optimum performance.

A heavy-duty work truck, my Sierra HD Denali had a MultiPro Tailgate, offering six functions and positions including a standing work station and easier access to the cargo bed. The primary gate opens using the key fob power release or a button on the gate. An inside panel at the top lip of the gate can be unlatched and raised to provide a vertical barrier for long cargo items.


The inner gate folds down for easier access to the box. The inner gate also includes a load stop panel. With the trailer hitch removed, the inner gate folds down into a large step, which will hold up to 375 pounds. A handle lifts up from the bed wall to assist with climbing.

Sierra’s two-tier loading design allows owners to insert a platform — a sheet of plywood for example — to separate items into two layers. The opened inner gate also provides a work surface at a convenient height, as well as extending the two-tier layer. A 120-volt A/C outlet is convenient for tools.

The bed had a spray-on liner with Denali logo, multiple tie-downs and a Gooseneck/fifth-wheel package ($545) including stamped bed holes with caps and a seven-pin trailer harness.

As a heavy-duty work truck, Sierra Denali has an innovative, expanded Prograde Trailering System to improve connecting and driving with a trailer. Features are accessible through the infotainment system and include: Trailer Light Test for one-person checking of brake lights, turn signals, etc; Customizable Trailer Profiles to save information such as trailer mileage, maintenance intervals, brake level settings, etc; Trailer Tire Pressure and Temperature Monitoring using a set of RF wireless sensors installed on the trailer wheels to send info to the app screen; customizable Pre-Departure Checklists on the screen with clear, illustrated examples of required steps; and Trailer Theft Alert to flash exterior lights and sound the horn if the trailer is disconnected while the vehicle is parked and locked.


The package also includes dynamic Hitch Guidance with Hitch View camera zoom. Many features of the trailering system can also be accessed and initiated through the My GMC mobile app, including the ability to share trailers and trailer profiles with other drivers.

ProGrade Trailering also includes auto electric parking brake assist, trailer sway control and trailer brake controller.

The Sierra Denali has lots of interior storage with large door pockets, multiple cup/bottle holders, armrest tray and large armrest bin with rails for file folders, shallow dashtop bin, two glove compartments anda 60/40-fold-up rear bench seat with storage package including bins in outboard seatbacks. Wireless charging, multiple USB ports and a 120-volt A/C outlet make using mobile devices easy and convenient.

The interior was also stylish and luxurious, with Denali-exclusive premium Forge Dark Walnut/Dark Ash leather seating, open-pore ash wood armrest and console trim and subtle dark-finish aluminum decor. Heated and ventilated front seats, heated steering wheel and heated outboard rear seats are standard.

A Bose seven-speaker audio system, Wi-Fi, Apple Car Play and Android Auto, SiriusXM, OnStar services and GMC Connected Access are standard. Teen Driver is standard, allowing parents to set controls and review teen driving habits.

The Back Seat Reminder is standard along with forward collision alert, lane-keep assist with lane-departure warning, automatic emergency braking, Intelli Beam headlights and adaptive cruise control with following-distance indicator. Front and rear park assist, lane-change alert with side blind-zone alert and rear cross-traffic alert safety systems are also standard.


A Perimeter Lighting System provides side-facing and wide-angle lights in eight distinct areas: within the tailgate handle cluster, as part of the reverse lights, within the rear corners of the bed, side mirrors and CHMSL cluster for dark worksites or driveways, campgrounds, or beaches.

Sierra Denali HD is designed for work, but comfortable and well equipped for family use. The navigation system was frustrating, with so-so voice recognition and spotty manual entry. Work functions, however — tailgate, trailering, etc. — were easy and convenient.

No EPA ratings are available, as these big trucks are exempt from fuel-economy rules. I averaged 16.5 miles per gallon, driving mostly on surface and neighborhood streets.

With freight and $13,660 in options, my Sierra Denali HD delivered for $78,955.


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