2021 GMC Yukon AT4 Towing Review: For Enclosed Trailers, Go Bigger or Differently

Look around any track paddock and you’ll see throngs of General Motors’ full-size SUVs. They’re a staple, and for good reason. Based on the GM half-ton pickup chassis, Chevrolet’s Tahoe and Suburban and GMC’s Yukon and Yukon XL offer a wagon-shaped pickup alternative that can tow open or enclosed trailers alike. I took a 2021 GMC Yukon AT4 to NASA Mid-Atlantic’s HyperFest weekend with my 20-foot enclosed trailer in tow to see if this latest Yukon could measure up.

2021 Yukon AT4

What Is It?

This is a 2021 GMC Yukon AT4. It’s the shorter wheelbase model – the longer being the GMC Yukon XL – but still has seating for six or seven depending on options. GMC redesigned the Yukon for the 2021 model year, with the biggest news being a fully-independent rear suspension that provides a better unloaded ride and more third-row and cargo space.

Also new for 2021 is the AT4 trim level. Meant for those who go off-road a bit more often than others, the AT4 comes with four-corner air suspension, Magnetic Ride Control (rapidly-adjusting adaptive shocks), a two-speed automatic transfer case, all-terrain tires, and software to help manage your driving both on-road and off.

AT4 sits toward the top of the Yukon trim levels, with the luxury-focused Yukon Denali above and more-attainable SLT/SLE below. GMC offers three engines in the 2021 Yukon lineup, but the 2021 GMC Yukon AT4 only gets one of them, the basic 5.3 liter V8. It produces 355 horsepower and 383 lb-ft of torque. Maximum horsepower comes at 5,600 rpm and peak torque just a bit lower at 4,100 rpm.

All engines are paired to the co-developed GM/Ford ten-speed torque-converter automatic transmission and above-mentioned four-wheel drive. GMC is making the more powerful, torquier 6.2 liter V8 available on the AT4 trim level for 2022 and beyond. The turbodiesel six-cylinder is available on other Yukon trims, but not here.

2021 Yukon AT4 interior

Every 2021 GMC Yukon is rated to tow at least 8,200 pounds, and the Yukon AT4 is no exception. GMC allows ten percent tongue weight – 820 pounds – and of course, a weight distributing hitch is recommended if pulling more than half the rated capacity. GMC also provides a VIN-specific sticker in the driver’s door jamb to indicate your particular Yukon’s tow capacity and payload, so you don’t have to guess about a thing. My specific Yukon AT4 was rated for 1,469 pounds of payload.

Given the Yukon AT4 sits toward the top of the 2021 Yukon model range, it’s no surprise that it’s a spendy SUV. MSRP of my 2021 Yukon AT4 included a $9,000 Premium Plus package and totaled $74,960 including destination.

2021 Yukon AT4 rear seats

Towing with the 2021 GMC Yukon AT4

My enclosed trailer sits squarely within the 2021 Yukon AT4’s towing capacity, coming in around 6,800 pounds with about ten percent tongue weight. The AT4’s cabin was a fine place to sit for the 250-mile tow to Virginia International Raceway, though I found the driver’s seat to be a bit firm. I wish that was my only issue with how the trip went, but alas.

GMC’s decision to offer the 6.2 liter V8 for 2022 in the Yukon AT4 is a smart one, as the 5.3 liter is simply not enough. It’s pretty slow unloaded – a full-throttle run down an empty VIR front straight was lackluster at best – and has to work hard (remember where on the tach it makes peak power and torque?) to keep speed up with a trailer attached.

2021 Yukon AT4 5.3L V8 engine

We live in a great world when 383 lb-ft of torque and 355 horsepower is “lacking,” and I also think the axle gearing is to blame. GMC equips every Yukon with 3.21:1 axle gears, likely in an effort to squeeze more fuel economy out of the vehicle. While the ten-speed transmission helps, shorter gearing would also make a solid difference.

Thankfully, that ten-speed pulls its weight in the powertrain, with quick shifts and smart gear selections. The shifter has become a series of dash-mounted toggles, with little + and – buttons to limit gears. I left the transmission in Drive and with the Yukon in Tow/Haul mode, it all worked out well with no intervention.

GMC also offers a trailer brake controller built-in to the dashboard, above your left knee. Trailer setup was simple when I first plugged in, and the controller provided seamless stops alongside the plenty-adequate truck brakes.

The biggest challenge the Yukon AT4 faced with my enclosed trailer was the aerodynamics of it all. The AT4 trim is soft. It’s sprung softly with blocky all-terrain tires, and those Magneride shocks can’t firm up enough to combat the spring rate. Choosing the Yukon instead of the Yukon XL means you get a 120.9-inch wheelbase instead of the XL’s 134 inches. Typically, a 120-inch wheelbase would be fine for a small enclosed trailer, but the rest of the tow vehicle has to be stiff enough to handle it.

2021 Yukon AT4

The short-wheelbase Yukon AT4 is all fine if your weekend adventures involve off-road trips, but I found the 2021 GMC Yukon AT4 relatively wallowy through corners, and easily upset when tractor-trailers passed. Choosing a street-focused Yukon would likely solve the problem, between the suspension and tire differences. If you really wanted the AT4, the longer Yukon XL AT4 would hide some of the softness behind the extra 13 inches of wheelbase.

Finally, fuel economy was average while towing – around 9 or 10 miles per gallon – but as with many large SUVs, fuel tank size is a problem. I had to plan for stops every 180 to 200 miles unless I wanted to coast into the Sheetz on fumes.

2021 Yukon AT4 towing enclosed trailer

Final Thoughts

The “large, body-on-frame SUV” segment is not the biggest, and given they can all tow about the same amount – the key reason to buy one instead of a unibody crossover – the competition is otherwise fierce. The 2021 Ford Expedition is the most competitive against the 2021 GMC Yukon and its siblings, and Ford’s 3.5 liter EcoBoost is a total monster with a trailer hooked up to the hitch. I was less enamored by the 2021 Nissan Armada, and the Toyota Sequoia is long overdue for a redesign.

An open trailer behind the 2021 GMC Yukon AT4 would have posed no real challenges. For those of us looking to tow a smaller enclosed trailer with a large SUV, though, there are better options that provide far more confidence behind the wheel. Some of those even come from GM, in theory.

While I haven’t spent time with every variant of their “T1xx” SUV platform, I think the GM sweet spot would be a longer-wheelbase Suburban or Yukon XL (or Escalade) and, ideally, the 3.0 liter turbodiesel six-cylinder. Retain the Magneride shocks and a more street-focused tire and spring (or airbag) configuration, and you’d be good to go.

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