The fourth-generation of the GMC Sierra heavy duty series came around in 2020. A few things entered the picture this year, like the uber-lux Denali Ultimate and the off-road AT4X models.
During a week or so with this 3/4-ton truck, I hauled around rocks and road tripped with the family. I did not, however, haul ass, because diesel trucks aren’t made for that.
Put down your virtual keyboard, coal rollers. It’s the truth. I was once in a Kenworth drag racing truck. It did not have a diesel engine. Diesel engines aren’t made for speed.
Now back to the GMC.
The Sierra 2500HD comes in a whole bunch of configurations. There are two-door, four-door and bigger four-door models (single, double and crew). There’s a 6.8-foot bed and an 8.1-foot bed. There are seven trim levels, two engines, and either rear-wheel or four-wheel drive.
These options can be whittled down somewhat for consumers. The seven trim levels can be knocked down to five, since the first two are mostly for fleet buyers. Of those, the SLT is the workaday option and the AT4 and AT4X are for those going off-pavement on the regular. The Denali and Denali Ultimate are for those with government contracts, oil money and residents of Jackson Hole.
After that, bed length will be determined by how comfortable you are with taking up two spaces at Walmart.
The engine choices are simpler. They’re both 6.6-liter V8s. One of them runs on gasoline (401 horsepower, 464 pound-feet) and one runs on diesel (470 horsepower, 975 pound-feet). Both have a 10-speed automatic transmission attached.
You buy the gasoline model if you want to save money, don’t pull heavy trailers often and have no need of a dually rear end. You buy the diesel model if you pull a lot of heavy trailers on the regular and/or need a dually rear end.
I’m personally a big fan of modern diesel engines. They’re efficient, powerful and predictable to work with. Paired with a good transmission like GMC chose for this Sierra 2500HD, they’re one of the best things to drive on the road. But they aren’t cheap. Both the up-front cost to add it (almost $10,000 in this case) and the added maintenance and fuel costs (urea, higher dollars per gallon) are big downers.
The model I drove was a 2024 GMC Sierra 2500HD Denali Ultimate with a single rear end, crew cab, standard bed and the Duramax diesel. Towing was rated at about 21,000 pounds, but other configurations of the truck can tow more.
For a week, I used this truck as a daily driver, toting the kids around town for various things. Grocery-getting and the like. We also went to the home of some friends and shoveled landscaping stones into the back of the Sierra 2500HD. It was, quite literally, a ton of rocks. It felt like a lot more.
I’m too old to be pushing wheelbarrows and running a shovel in 90-degree weather. I fully admit to pretending at “problems” that needed to be fixed so that my teenagers would end up doing the majority of the manual labor. Age has some privilege.
When we were done, that ton of rocks didn’t look like much in the back of the GMC. And we were only about halfway to its full cargo capacity of about 3,900 pounds. It was a little disheartening, to be honest, to see all that work amount to just a little pile of stones in the center of a huge truck bed. We still had to unload them too. Needless to say, there was ibuprofen and electrolyte mix involved that day.
The next day, still gluttons for punishment, we threw our bags into the bed of the truck and all five of us (my wife, three kids, myself) climbed into the 2024 Sierra 2500HD and began a road trip down to Pueblo, Colorado.
The upside to a huge vehicle like this in Colorado traffic is that you automatically gain some respect from the speedsters in their Prius and smart car choices. The downside is that, like most Colorado drivers, they still seem to have a death wish. But at least they hesitate for a moment before doing their witless maneuvering.
Once in Pueblo, we greatly appreciated the aggressiveness of the air conditioning system in the GMC Silverado.
As a road trip vehicle, the Silverado 2500HD is much better than the same truck would have been two decades ago. The smooth-shifting 10-speed makes driving more car-like, comfort-wise, and gives the big diesel engine a chance to stay within its golden RPM range for efficiency and power delivery more often. And with 36 gallons of fuel on board, it has a lot of range before needing a refill. Our fairly light load (five people, half a dozen suitcases and bags) meant that we were closing in on 18 mpg on the highway with this truck. Not bad for a diesel heavy-duty.
Now I await the inevitable commentary about how this truck should have been tested on a Wyoming ranch with 400 head of cattle and 50 bales of hay in the back or whatever. And I say: No, it should not have. See the criteria for ownership above. I drove the Denali Ultimate model. Know your role.
