A truck in every sense of the word
To understand this truck, you have to look past the imposing Vader Chrome grille and dive straight into the engineering. This is where GMC has made its most deliberate and defining choices. Under the continent-sized hood lies the familiar 6.6-liter L5P Duramax turbo-diesel V8. On paper, it produces 470 horsepower at a diesel-idling 2,800 rpm and a tectonic 975 pound-feet of torque at just 1,600 rpm. That last number is the key. This engine is engineered to get a 10-ton load moving from a dead stop without breaking a sweat, and it does so with a distant, well-mannered rumble.
That power is channeled through an Allison-branded 10-speed automatic transmission. In the heavy-duty world, the Allison name carries the same kind of brand equity that Brembo does for brakes or Recaro for seats. It is synonymous with industrial-grade durability. Its party trick is not just the sheer number of gears, but the intelligence of its shift logic. It works to stay planted in that thick, 1,600-rpm torque sweet spot, whether you are climbing a grade or merging onto the highway.
Kyle Edward
But the powertrain is not the Denali Ultimate’s secret weapon. That title belongs to the chassis, specifically, its front suspension. While its rivals from Ford and Ram stick to the traditional, solid front axle, the Sierra HD employs an Independent Front Suspension, or IFS. This is a fundamental engineering divergence. A solid axle is simpler and offers massive articulation, which is excellent if you are building an extreme off-roader or a municipal snowplow. An IFS, however, allows each front wheel to react to bumps independently. The technical advantage is a leap in ride quality and steering precision. Having driven all of the large trucks, I can safely say the Sierra 2500 HD offers the best ride quality and greatest on-road precision. For the Denali Ultimate customer, who is far more likely to be navigating a long highway journey with a travel trailer, this is the superior choice.
This is all backed by a fully boxed, high-strength steel ladder frame. The rear suspension is a more traditional solid axle with multi-leaf springs, the typical design for handling the colossal tongue weights of fifth-wheel trailers. For braking, it relies on four-wheel-disc brakes and a standard diesel exhaust brake. A flick of a switch turns the engine into a powerful compressor, using back pressure to help slow the truck on descents.
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A tremendous driver despite its size
So, how does all this engineering translate to the real world? For such a large truck, the driving dynamics are excellent. The IFS system pays dividends, filtering out the harshness and vibration that plague its solid-axle competitors. The ride is composed and comfortable, not overly stiff or jarring, even when the bed is empty. It manages to feel smaller than its colossal footprint suggests, with a directness to the steering that is genuinely surprising. It is, without question, the best-riding, best-handling heavy-duty truck I have ever driven.
The Duramax powertrain provides a seemingly bottomless well of torque, and while it is no slouch, there is truth to the parking lot gossip: a competing Ford Super Duty with the high-output 6.7-liter diesel does feel quicker off the line. That truck, with its headline-grabbing 1,200 pound-feet of torque, simply has more brute force.
Kyle Edward
In my opinion, this is the best-looking heavy-duty truck on the market. It manages to look both premium and purposeful. The Denali Ultimate trim, with its exclusive dark Vader Chrome grille and unique 20-inch gloss-black wheels, looks menacing and sophisticated. There is an excellent use of LED accents, from the animated “welcome” sequence of the projector headlamps to the signature C-shaped taillights. It looks like it is here to get the job done, but with a premium feel that, in my opinion, eclipses the high-end offerings from both Ram and Ford.
Functionality beyond the power
The real-world functionality is just as impressive. The power-retractable assist steps are a necessity for climbing into a cab this high. Then there is the MultiPro Tailgate, which is still a great feature in the truck world. It is a six-function piece of origami that can be a step, a load stop, a work surface, or just a regular tailgate. The Ultimate’s version even includes a weatherproof Kicker audio system built right in.
The 2025 Sierra 2500 in Denali Ultimate trim has, most certainly, the nicest HD truck interior you can buy. The exclusive Alpine Umber colorway is stunning, with swathes of full-grain leather covering the seats, dash, and door panels. This is not the stiff, plastic-coated stuff; this is nice, soft-touch saddle leather. It is paired with beautiful, authentic, open-pore Paldao wood trim, which even features laser-etched topographical maps of Mount Denali.
Kyle Edward
Kyle Edward
The driver and front passenger are treated to 16-way power-adjustable, heated, ventilated, and massaging seats. The driving position is commanding, and visibility is excellent. A premium microsuede headliner and a 12-speaker Bose sound system elevate the entire sensory experience.
The cockpit is dominated by a trio of screens: a 12.3-inch configurable digital instrument cluster, a massive 15-inch multicolor Head-Up Display, and a 13.4-inch central touchscreen. This system runs Google built-in, which means it has the speed, intelligence, and voice-command of Google Maps and Google Assistant baked right in. It is fast, intuitive, and a massive step up from older infotainment systems.
The ProGrade Trailering System offers up to 14 different camera views. The most impressive is the “Transparent Trailer View,” which stitches together camera feeds to make your trailer digitally disappear, allowing you to see traffic behind you. Paired with Adaptive Cruise Control that is calibrated to work while towing, it is the most comprehensive and confidence-inspiring towing suite available. The as-tested MSRP for this truck hovers around $98,000.
Kyle Edward
Final thoughts
So, what is the final verdict on the 2025 GMC Sierra 2500 HD Denali Ultimate? This truck offers a class-leading interior, a surprisingly sophisticated ride, and industry-leading trailering technology.
About the author
Kyle Edward
Editor-in-Chief, Autoblog