2021 GMC Yukon AT4 Long-Term Review: A Year of Towing

gmc yukon Full Overview

Towing ability is one of the most important but often overlooked characteristics of full-size SUVs and pickups. With the incredible increase in popularity of travel trailers, side-by-sides, boats and other towable outdoor toys in recent years, it’s more important now than ever that a person’s tow vehicle is up to the task. It doesn’t just mean having a high enough maximum pull rating. A competent tow vehicle must exhibit stable handling and the ability to keep vital fluids cool, the power to climb steep hills, the braking to safely back down them, and enough fuel range to avoid being stranded. After a year on the road with our award-winning 2021 GMC Yukon AT4 and 4,500 miles of trailering, we’ve had the opportunity to evaluate all of these key elements. Here’s what we found.

5.3-liter V-8 engine power

When GMC’s all-new Yukon AT4 entered our SUV of the Year contest for the 2021 model year, the off-road SUV was offered only with the company’s 5.3-liter V-8 engine. This engine produces 355 hp and 383 lb-ft of torque. At the start of our test, we bemoaned the fact that the Yukon AT4 wasn’t available with the more powerful 6.2-liter V-8 engine, rated at 420 hp and 460 lb-ft. GMC rectified this in 2022 by adding the larger gasoline engine to the lineup. But after driving the 6.2-liter V-8-powered Yukon AT4, and after spending a year with the 5.3-liter V-8, we’d make the bold claim that the bigger engine isn’t necessary. Towing with the Yukon AT4 at maximum load, we almost never longed for more power. The SUV easily maintains the posted speed limit up even the toughest grades, including passing slower traffic on California’s infamous “Grapevine.” Bottom line, save $3,420 and skip the 6.2-liter.

Maximum pull rating

There’s a lot more to the “how much can I draw?” equation than just the maximum rating. Thankfully, GMC makes it incredibly easy to know what these maximum numbers are for your specific vehicle. Our long-term 2021 Yukon AT4 arrived with a maximum towing capacity of 8,200 pounds, a maximum payload of 1,470 pounds, a gross weight of 7,500 pounds, a curb weight of 14,500 pounds, and an indicated curb weight of 6.00 kg. . If you’ve ever tried to decipher another manufacturer’s weight matrix, you know how invaluable it is to have this information on your doorstep.

To see how close we came to breaking those ratings, we drove our fully loaded Yukon AT4 and towed over a CAT wave at a Pilot truck stop. Doing this costs next to nothing ($12 at time of publication) and we recommend it for anyone who tows a trailer regularly. We topped the scale with a trailer weight of about 8,300 pounds and a total gross weight of 15,660. Even with our careful planning, we overloaded the Yukon AT4 by about 1,160 pounds.

How does it happen? Simply put, when towing a trailer with the maximum 8,200-pound capacity, the 14,500-pound gross rating and 6,030 curb weight leave only 270 pounds for payload. You can see the problem. When we added two adults, two children, an ARB fridge/freezer and tools for two weeks on the road, we quickly exceeded our remaining 270 pounds.

We mention this not to condone it (although the Yukon AT4 handled the load with ease) but rather as a cautionary tale. We knew our trailer weighed close to 8,000 pounds, but we had failed to actually sit down and do the extended math. Knowing that we would have four people and supplies in the Yukon while towing, we should have known that the actual maximum trailer weight would need to be closer to 7,000 pounds. We also want to encourage everyone to get their trailer weighed as well, as the manufacturer’s rating is often very far off.

Fuel economy and Range

Range is arguably more important than fuel economy when towing. The overall range can be increased with either better fuel economy or a larger fuel tank. We’re here to report that our 2021 GMC Yukon AT4 offered none of these. Our single biggest complaint when towing the Yukon AT4 was its inability to travel some marketable distances, mainly due to the vehicle’s paltry 24-gallon fuel tank capacity. We know third seat legroom is important and the new independent rear suspension takes up a lot of real estate. However, it would be good if GMC could find room for another 6 liters.

Looking back at our first look at the Yukon AT4’s towing capabilities, we may have been a little too optimistic. At the time, we thought the Yukon could average 12.6 mpg when towing our 21-foot toy dump truck. During subsequent tests with the same trailer, including a recent 2,400-mile trip, we averaged just 8.46 mpg towing. We’ve seen as high as 10.25 and as low as 5.82 mpg. This means stopping every 150 to 170 miles to avoid getting too close to the bottom of the tank. In fact, on a recent trip up the Kingman grade on I-40 in Arizona, we saw the indicated fuel range drop from 60 miles to 0 in just 8 miles. When we got to town, the Yukon took 23,384 liters. It was close.

Braking, handling and correct tire pressure

Overall, we couldn’t be happier with how our 2021 GMC Yukon AT4 handles when attached to a trailer. Our Yukon AT4 came equipped with adaptive air suspension and magnetic ride control dampers. This meant that it could keep the rear of the car perfectly level even with a heavy load on the bumper. While this worked great for our flatbed truck, the air suspension is no substitute for a properly set weight distribution and sway control hitch, which we always used with the larger trailer.

We found that directional stability with a trailer in tow was almost as good as it is without—until wind is involved, that is. Mild crosswinds were easily dispatched by the Yukon. However, strong wind can give a more white-knuckle experience. We found that the key to happy hauling at maximum weight is to keep the vehicle speed reasonable. This applies to all towing vehicles but is even more important when the trailer is larger than the vehicle pulling it.

Braking was also more than effective with the Yukon AT4. Even with our trailer’s auxiliary brakes engaged, the Yukon easily controlled the load. That said, as a general rule we wouldn’t recommend towing anything as heavy as our trailers without additional trailer brakes. We also found the gearbox’s braking strategy worked exceptionally well, automatically downshifting aggressively on downgrades. When we wanted to keep the vehicle in a certain gear, a quick press of the “L” shift button had us set into a maximum gear, which the Yukon happily held.

The key to good handling and braking with a trailer in tow is proper air pressure. The 2021 GMC Yukon AT4 comes with large 275/60R20 Goodyear Wrangler Trail Runner AT tires. Standard tire pressure is set at 35 psi for normal highway use. However, tires reach their maximum load at 50 psi. We noticed a lot more tire spin and overall “squishy” handling when towing at street pressure. After bumping up to the recommended maximum, the Yukon became a completely different and much more confident towing vehicle. The higher tire pressure and resulting firmer sidewalls made all the difference. Regardless of the vehicle used for towing, it is always important to check the tire pressure.

Towing or not – our final thoughts

We have pulled many different trailers with as many different vehicles. With this knowledge, we can definitely say that the 2021 GMC Yukon AT4 is a perfectly capable towing vehicle. Yes, you have to pay attention to how heavy your trailer is in relation to how much payload (including people) is inside, and you have to be prepared to stop for gas every 150 miles or so. Those things aside, we wouldn’t hesitate to tow any reasonable trailer across the country with the Yukon AT4. And we’d be happy to recommend the Yukon AT4 to anyone looking for a tow vehicle that also seats seven adults and can hit the backcountry with confidence. This SUV really can do it all.

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