2019 GMC Sierra AT4 Review – Behind the Scenes

Carbage Online got the chance to review the 2019 GMC Sierra AT4 for a span of eight days. What was learned and how did it fare in testing? This article answers those and more with some behind the scenes photos from the video review.

If you want to know the technical details of the T1XX chassis, you’ll want to check out the article I did last year when I took photos of the AT4 at the Proud Bird. That goes into deep detail about the chassis, what’s offered for engine choices, and more details there. This article, however, is all about driving it around the city of Los Angeles and up to Hungry Valley SVRA for some off-roading over the span of eight days.


Let’s start off to say this isn’t a numbers form of testing. Rather, it’s my opinion on how the truck did for my normal day-to-day. So, this meant driving in and around Los Angeles, Ontario (California), and up to the Gorman/Pyramid Lake area. So, there won’t be hard numbers like dyno sheets, 0-60 times, or anything else that would give you data that you probably wouldn’t use if you were to own the truck yourself. Let’s face it, those numbers are mostly for phallic measuring (sorry, bench racing) than most real world use.

In fact, the first thing I did with it was drive it to the Petersen Automotive Museum for the opening of the Bruce Myer Collection. I took advantage of their large, upper parking garage to get nighttime photos using my new light setup. The truck was under the height limit, but just as the antenna aerial (the little ball at the top of the antenna) would contact some of the lower parts of the structure but nothing else was that high on the body of the truck. So, if low structures are in your future, you will want to be sure you can fit. However, most parking garages aren’t that low, either.


Gas Guzzler?

From that point on, I used it as if it were my daily driver. Getting groceries, traveling around, and getting from place to place. The positive thing I can report is that the 6.2-liter isn’t that much of a fuel hog. With Auto Start/Stop, direct injection, and cylinder deactivation along with my driving habits (staying within five to ten-MPH of the speed limit and no “jack rabbit” starts), the 6.2-liter got nearly the same fuel mileage as my 2000 Nissan Pathfinder at 18-MPG average.

In a few cases, it got even better mileage than the Nissan VG33E. At one point, I was able to get as high as 24-MPG. No, these aren’t hybrid vehicle hyper-mileage but it’s an astounding average for such a large, auto-four-wheel-drive truck with 376-ci. The only downside is that to get the best performance out of it, you need to use premium fuel or the poor excuse for premium we get here in California – 91-octane.

That’s not to say you can’t use regular as direct injection and the ability to more finely control fuel by the PCM allow you to use less than premium if you want. You just won’t have maximum power or potentially worse fuel mileage as it injects more fuel to control cylinder temperatures and prevent knock.



Overall, driving the AT4 is easy once you get used to the physical size of the truck itself. The steering never feels too light or heavy despite using electronic assist rather than hydraulic. The brakes feel firm and planted, though maybe a little light while in four-low as it takes more pressure to keep the truck still. The electronic throttle was more responsive than older (2016 and under) GMs did with their e-throttle system, though, you knew you didn’t have direct control like a cable throttle gives you. The ten-speed transmission also felt smooth and you never really knew it had as many gears as it did.

Daily driving the Sierra AT4 was a pleasure and something I don’t tend to experience when driving a truck save for the current Honda Ridgeline. However, where the Ridgeline feels stable while driving thanks to its four-wheel-independent suspension and coil springs, the AT4 is still a tiny bit rougher because of its leaf springs and solid rear axle.

Don’t read that as a demerit against the AT4, though, as it does have a much higher payload and towing capacity than the Honda. The Ridgeline comes in with a maximum payload of 1580-pounds and capable of towing up to 5000-pounds. The AT4 can tow up to 9400-pounds and haul up to 1765-pounds in the bed.


Speaking of the bed, I must call attention to GMC’s gimmick called the MultiPro Tailgate that’s standard on the AT4 package. Don’t get me wrong when I use the word “gimmick,” it’s a neat and potentially useful feature that’s optional on Sierras. I don’t take regular trips to the hardware store to buy random, long pieces of wood, so I didn’t have a use for it.

Despite that, when I showed this special tailgate to my friends inside and out of the industry, they all really seemed to like the idea. Especially so when they realized it could be used as a true bench and would be more comfortable to use over a standard tailgate.

So, it has it’s use and selling points and why I do call it a gimmick, but if you’re not using it that way or to haul long pieces of stuff, you’re not going to see the value. Though, it does make for a great step that held me up so I could climb into the bed if I wanted to.

Tonneaus and Tires

The AT4 I tested also came with a tri-fold tonneau cover. While it was useful, it also needed “finesse” to get it to close properly. I thought it was me until I saw the handler also having to close it a couple of times before it would latch properly. It may be a design or it may just be because it’s a press loaner, too.

These vehicles take some abuse from journalists and it why I’m not going to comment on the Goodyear Wrangler Duratrac tires. They are good tires with decent grip and feel great on pavement, but this set was quite noisy. The roar could just be heard over the quiet cabin, but, again, it might not be because of the tires. It could have easy been the mooks before me abusing the truck in their “testing.”

Add in that most of the owners of these same tires don’t complain much about it, too. They have an aggressive tread for all-terrain tires and worked great in the sand and dirt without feeling like they would give up grip on a wet surface (yes, it rained in Southern California and while I was testing this truck). Typically, tires with larger blocks don’t feel stable and are more prone to hydroplaning in the wet and I never experienced that while driving in the dry or unusually moisturized roads.


For most of the trails that carve out the Hungry Valley SVRA, the AT4 was never too big. Only in a very few spots and where there was fallen brush thanks to the weather we’ve had, I never felt like I had to take a real easy while driving the Sierra. If I felt like I was going to get stuck or just needed the extra torque to get up a steep hill, I would use four-low. Otherwise, I kept it in auto mode and set it to “Off-Road.”

GM also makes one of my favorite hill decent assists on the market. It activates and you barely know it as it makes only the slightest bit of noise. When compared to the Toyota Tundra or Tacoma, it’s essentially silent as those units sound like something is going wrong and make a huge racket, well, at least when I tried them out back three years ago.

If there was one thing I would get rid of on this truck, on this particular build kit of options and accessories, it would be the running boards. As many owners have pointed out, the running boards reduce your ground clearance despite the AT4’s two-inch height advantage over the standard Sierra 4WD. On Hungry Valley’s Frame Twister, it was very apparent and it is designed to cause bottoming on stock or lightly lifted vehicles, but even traversing many hills the running boards would impact and pull some Earth with it.

Cameras, So Many Cameras

I’ll admit, I haven’t been in very many new trucks since the Honda Ridgeline, but I haven’t been in a vehicle with so many cameras. You have a camera on the grille, one on each outside mirror, one on the roof by the high-mount stop light, and two on the tailgate. The oddball, the one on the high-mount stop light, is the camera for the inside rear-view mirror.

This was easily the best feature I’ve used when it comes to cameras on vehicles. It’s live and real time as you drive, meaning it will fully adjust for a driver with bright lights without you noticing it. However, you’ll also know which drivers have LED lights as the camera is out of sync and show LED lights flickering while they are constantly on to the human eye. The other cameras combine to give you some of the best views one could ever need while parallel parking (yes, I parked the AT4 outside and had to parallel park it whenever I was finished driving it).

Those camera views were shown in the head unit and you never really had a blind spot. I do wish it would turn on the front camera while in four-low and the outside mirror cameras when you’re trying to perform a lane change as that would assist while driving on California’s highways and its drivers that lack attention, patience, common sense, and the ability to use a turn signal. Though, the blind spot warning lights in the mirrors were helpful in exchange for the cameras.


A Heads-Up Display That Actually Works?!

Yep, you’re reading that correctly. For the first time in my experience, the heads-up display in the AT4 was not only useful but also visible at nearly all times during the day. I had it setup to read just above the dashboard showing the lane keep assist, speedometer, and speed limit displayed.

I legitimately found it very useful as I had no need to peer so far down and away from my line of site as I was driving. For this truck and my height, I would need to take my eyes fully off the road to see my speed where as it was a far quicker glance to the HUD. It also helped me maintain the speed limit easier as it showed what the limit was for the road I was on and just beside my actual speed. It also had a multitude of display options, brightness, and placements, but how I had it was useful to me.

The Important Question: Would I Buy It?

Despite some minor faults, I wouldn’t hesitate to purchase a Sierra AT4 with the 6.2-liter V8. I would leave off the running boards and tonneau cover. It would also be nice to make the MultiPro Tailgate optional on the AT4. They aren’t horrible – well, except for the running boards and the reduction of -ground clearance –they just aren’t for me.

Everything else about it is perfect for a high-end, four-wheel-drive truck. The only other gripe is the price – the AT4 starts out with a $50,800 MSRP for the 5.3-liter Double Cab while the 6.2-liter with a short box and crew cab (like this one) starts out at $55,695. The tester, as built, would MSRP for $64,960. Now, I know, anyone worth their salt wouldn’t buy at MSRP. You shouldn’t and you should haggle for the best price possible. It’s just still unbelievable that I can say this truck could cost anything close to $51,000 – let alone $65,000 –with a straight face.

Closing Question for You

However, even a fully-optioned 2019 Ford F150 Lariat FX4 isn’t much cheaper at $60,845. So, what is the breaking point? Would the $4,115 difference between the two turn you off from the AT4? Or the fact that the FX4’s best, most powerful engine makes 470-lb-ft of torque but is a turbocharged 3.5-liter V6 while the 6.2-liter is a traditional V8 but only makes 460-lb-ft of torque? I wouldn’t mind hearing your opinion on it so sound off in the comments!

Be sure to also check out the full gallery linked right here!


Justin Banner

Justin Banner, Lead Editor and Founder of Carbage Online, has been involved with the automotive media and industry in many capacities and now tackles publication ownership with CarbageOnline.com. Prior to that, he has freelanced for top online publications of modern media that include Speedhunters, MotoIQ, Super Street Online, Hot Rod Magazine and many others. All due to his nearly 20 years experience as a mechanic, service writer, and technical support in the automotive industry. Justin is also a Journalist Level member of the Motor Press Guild - an industry recognized entity of professional automotive journalists - since 2015.