The pickup truck has long since graduated from being a tool [You’re a tool. —Ed.] into a lifestyle vehicle, and with that lifestyle-ification has come more luxury frills and off-road capability. This preponderance of pomp and prosperity has generally been reserved for “light” duty half-ton trucks, with the more serious “heavy duty” trucks being left a little more utilitarian — until fairly recently. Ford’s F-250 Platinum has leather-lined Lincoln chairs, the Ram HD Limited rides like a cloud on air suspension, and now, GM has extended its new Ultimate treatment to the updated 2024 GMC Sierra 2500 HD Denali Ultimate.

Unlike the Silverado HD, the perpetually handsome Sierra never had an issue with style. As such, the Sierra HD’s facelift for 2024 is pretty subtle but effective at keeping it contemporary. It borrows a lot from the 1500, including a very similar — read: huge — grille treatment and LED headlights with fancy sequential turn signals. The new Ultimate trim gets a “Vader” grille that darkens the bling down to a sinister satin finish, accented by blacked-out badges and prominent Ultimate badges on the fenders.

Those big badges indicate what’s being hidden by the even bigger grille: a reworked 6.6-litre Duramax diesel V8 engine, benefiting from a new turbocharger with variable vane geometry, more aggressive injectors, new heads, and new engine management. It produces 470 horsepower and 975 pound-feet of torque, but it’s more than just the raw numbers. It’s the torque spread of this monster motor; GM put all that power way down low in the rev range to improve drivability and acceleratio — with or without a 19,300-pound trailer behind you.

Maximizing might is only part of the story. GM’s trucks are now the only consumer-grade trucks on the market featuring an Allison transmission, as highlighted on the fender badge. It’s a 10-speed unit, and is one of the best transmissions on the market for any application, at any price point. So far as I can tell, it is without flaw. Slick, smart, seamless, sharp — you name it, this gearbox does it all, and does it masterfully. It’s not locked away in an ivory tower with the Duramax engine, either. It’s now standard with every HD Sierra, including the 401-horsepower, 6.6-litre V8 gasser.

Beastly as the diesel engine may be, it certainly doesn’t feel or sound like it nearly as much as you’d expect. It’s impressively quiet and refined, lacking a lot of the typical mechanical clatter you’d expect from a burly diesel. Power delivery is pretty linear — once you get used to having nearly a thousand twisticles available from just 1,600 rpm. Acceleration is surprisingly rapid for how huge this thing is, even if it’s not quite as all-out ravenous as Ford’s new High Output Powerstroke. Stay out of the throttle and it’ll return 17.2 L/100 km of fuel use in mixed mileage, but that swells real quick if you’re in even the slightest hurry.

I can’t imagine why you’d be in a hurry. The Denali Ultimate’s cabin is absolutely lovely; a near-direct lift from the excellent Sierra 1500 Denali Ultimate. All Ultimates get the same interior, a two-tone black and baseball-glove-brown affair complete with contrasting cross-stitching and piping to accentuate the sumptuous full-grain leather. The dash is dressed with matte Paldao wood trim, with a topographic map of Mount Denali in Alaska engraved. Nerdy, yes, but a cool design all the same.

Also nerded-up is the infotainment, which now gets the same Google-powered software, attractive layout, and crisp 13.4-inch touchscreen from its lighter siblings. It generally works quite well and is very easy to use, and there’s a good blend of physical and touchscreen-based controls. Some minor gripes: I don’t love that the climate buttons are piano black, I really don’t love that the volume knob is blocked by the column-mounted shifter when in drive, and I loathe that on two occasions, the Bose Audio system refused to work. At all.

Googling it — yes, I know, ironic — showed that it’s a common fault that’s new to the software. It’s cured by shutting the truck off, walking away from it, locking it, and trying again. Very irritating when you’ve got somewhere to be and are afraid of being alone with your thoughts. [I’ve heard Nathan’s thoughts. All he thinks about are Porsche 928s and bananas. Literal bananas. —Ed.]

You’ll hear those thoughts clearly because the cabin is properly hushed, impressively well removed from wind and road noise, with only the distant din of the diesel mill to keep you company. The Sierra rides better than its Ford rival, and handles better than both its Ford and Ram rivals, thanks in large part to its independent front suspension. Its structure is rock solid, largely lacking in the chassis shudders that afflict heavy duty pick-ups with the even-heavier-duty suspenders that come with them. It’s comfortable, and with the Sierra’s relatively communicative and well-gauged controls, it’s easy enough to pilot.

It even manages to avoid being that much of a bear in urban settings, thanks to an impressively tight turning radius and a plethora of digital peepers and beepers placed all around the truck. They go a long way to helping you out when things inevitably get tight in town. I personally made generous of the cameras smartly mounted on the bases of the side mirrors to avoid crunching my own car when coming home under the cover of darkness. I also appreciate that they’re mounted on the bases of the mirrors and not the ends, so you don’t lose use of them if you have to fold the mirrors in. If all this parking talk stresses you out, you can get a massage from the seats to settle you down again.

The 2024 GMC Sierra 2500 HD Denali Ultimate does it all, blending the best of what GM has to offer in every regard — handsome style and commanding presence, classy interior design adorned with top-shelf materials, good use of technology for both comfort and convenience, and above all, serious hardware and slick engineering chops to tie it all together. While a base Sierra HD with a regular cab and cloth seats starts at $64,599, our decked-out Denali Ultimate with all its decadent trimmings rang in at nearly double that: $124,474 as-tested. Whether its extra style and fancier chairs are worth the extra ten grand over a Silverado HD High Country is up to you, but I wouldn’t judge you for indulging in the Ultimate lifestyle.