2026 GMC Sierra 1500 Denali Ultimate: Towing Pros, Cons and MPG

What Truck Shoppers Need to Know

• The GMC Sierra 1500 Denali Ultimate’s powertrain is great for towing and pulled our nearly 5,000-pound trailer easily.
• Unfortunately, the Denali Ultimate doesn’t offer towing mirrors from the factory, and it’s a multistep process to use engine braking to manage the truck’s speed on descents.
• The Sierra 1500 Denali Ultimate got around 10 mpg when towing versus 23 mpg unladen.

Over the past decade, a not-so-quiet battle has been raging in the light-duty pickup truck segment. Ford, GM, Ram and Toyota are all-in on creating more upscale trim levels to outdo their competitors. GMC’s entry into the fray is the Denali Ultimate, but I’m not here to talk about massaging seats, leather upholstery or the many safety features packed into these high-end trucks. No, I’m here to test their towing mettle in the mountains of Utah.

Related: 2024 GMC Sierra 1500 Denali Ultimate Review: Reaching for the Crown

The Route

My towing route is 63 miles long and includes freeways, city streets and mountain highways. It offers long straights and plenty of twisty sections, with a very steep and slow jaunt up to a wonderful view. Speed limits range from 25 mph up to 70 mph, and elevation starts at 4,550 feet and climbs up to 5,650 feet. During this test, temperatures were cool, ranging from the upper 30s Fahrenheit to the mid-40s.

Towing Pros

Powertrain

The route starts by exiting a gas station and entering straight onto a freeway. With the powerful 6.2-liter V-8 engine that’s paired with a 10-speed automatic transmission, the GMC 1500 had no issues getting the 4,850-pound billboard of a trailer up to speed. The engine makes a stout 420 horsepower and 460 pounds-feet of torque, and the 10-speed automatic does an excellent job of keeping the V-8 in its torque range without over-revving the engine and burning fuel unnecessarily.

Trailer Brake Controller Location

Most new pickup trucks include trailer sway control, trailer blind spot monitoring and an excellent factory trailer brake controller when equipped with towing packages. This makes the chances of needing to manually activate the trailer brakes low, but high winds and/or an improperly loaded trailer can still cause unexpected sway. GMC puts the trailer brake controller directly in front of the center armrest, making it visible and accessible for both the driver and front passenger. It’s the best placement in the industry.

Adaptive Ride Control

Across nearly any terrain, GM’s adaptive shocks are extremely effective. In this test, the shocks firmed up nicely to handle the load of the trailer without resulting in a stiff ride. These shocks work wonders in everything from a Chevrolet Corvette on a track to towing with this Sierra 1500.

Gauges

When towing, the tow vehicle is going to experience more stress than during a typical commute. The added load can cause excess heat and wear, and having good information is critical for catching a heating trend or battery/alternator issue before it becomes a major problem. In the Sierra 1500 Denali Ultimate, the battery gauge disappears and is replaced by the transmission temperature gauge whenever the Tow/Haul mode is activated. For even more clarity, the transmission temperature can be displayed in the driver information center with a numerical readout instead of a bar gauge. Coolant temperature and oil pressure can also be displayed, which is another big help. These readouts cover the three most critical areas.

While it was nice having this information, there is still some room for improvement. It’d be nice to have an oil temperature gauge and be able to see what gear the transmission is in without having to push the gear selector into L.

Super Cruise

This one came as a surprise to me as I’ve never been a big fan of driver-assist features. I’ve fought with them due to weather changes, light changes (like the shadow of a mountain) and construction zones, which can confuse these features.

But even in a luxury truck, towing long distances can be fatiguing on the driver. The Super Cruise hands-free driving system can reduce that when used on open freeways with clearly defined lane markings. When the system worked, it worked well. That said, it still had multiple failures in the challenging situations mentioned above. One time, it asked me to take the wheel, and I did, but even after giving the steering wheel a few jerks, it didn’t recognize that I had control of the vehicle and disabled Super Cruise until the truck was restarted.

Honorable Mention: Vehicle-Specific Trailering Capacity Info

One more feature that is really nice to have is a trailering-information sticker that’s visible when you open the driver’s door. This provides vehicle-specific information on payload, tongue weight and towing capacity, so there’s no need to search the owner’s manual or online to find a best guess for the truck’s actual towing capacity. It’s clearly listed on the sticker, and in this case, it was 8,900 pounds.

Towing Cons

Narrow Side Mirrors

While GMC does offer towing mirrors through GMC Accessories, they aren’t optional for the Sierra 1500 Denali Ultimate from the factory. My test truck’s standard side mirrors weren’t quite wide enough to reach out past the edges of the trailer to see along its sides, though you can see any vehicles in the lane next to the trailer. Two additional features that lessen this issue are the trailer blind spot monitor and the side-view camera system that automatically activates when the turn signal is engaged.

Offset Rearview Camera

Factory software programming for offset rearview cameras has improved markedly over the past five years or so. However, the best solution is still to have the camera centered. GMC offers multiple camera views that greatly help in aligning the hitch with the trailer, but the issue still arises because the camera is angled instead of directly over the truck’s receiver. I know rearview cameras are sometimes offset for cosmetic or functional reasons, but it’s always a miss for me in a tow vehicle.

Paddle Shifters?

The Sierra 1500 Denali Ultimate has steering-wheel-mounted paddle shifters. They are small and out of the way, so they’re hard to accidentally engage. In fact, you cannot engage them by simply clicking on them; you first have to move the gear selector from D to L. The L position functions more as a gear limiter; if you shift into L from a stop, it will limit the transmission to 1st gear, and if you do it while driving, it will automatically limit the transmission to one gear lower than what was previously being used in Drive. Once L is engaged, the paddle shifters can then be used to select the highest gear the truck can be in; the transmission will shift normally through the gears up to the highest one set.

When descending and trying to quickly downshift to use engine braking, the whole process isn’t quick; first shift from D to L, then use the paddle shifters for additional gear reductions. It would be nice to always see what gear the truck is in and to always have the paddle shifters available when the truck is in Tow/Haul mode.

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Real-World Gas Mileage: Towing

Most pickup trucks I’ve tested on this route with this trailer have returned between 9 and 10 mpg, and the Sierra 1500 Denali Ultimate’s fuel economy was right in line with this. Over the 62.9 miles the truck logged, the trip computer showed 9.9 mpg. Calculated fuel economy based on consumption of 6.28 gallons of gas was 10 mpg.

Real-World Gas Mileage: Unladen

Even after testing multiple half-ton trucks with V-8 engines, I’m always surprised by how efficient they can be when unladen. The trip computer showed 23.1 mpg over 62.8 miles, while calculated fuel economy based on 2.8 gallons of fuel was 22.4 mpg.

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