2020 GMC Sierra AT4 1500 Diesel

Diesel power took a beating from various companies playing fast and loose with the emissions rules.

But given that the biggest blow to the environment for any vehicle is its manufacture, the most environmentally friendly vehicle is the one that lasts the longest. Diesel engines easily win here, as they usually last twice as long as gasoline engines. So the smarter car companies stick with Rudolf Diesel’s invention. No arguments from me.

Example: GMC Sierra AT4 full-size pickup truck.

My tester was actually a 2020 model, but the 2021s just arriving are basically identical. My truck started at $63,098 and loaded with options, listed at $75,918. That’s big money.

Now, as a diesel, it gets good fuel economy. Why would anyone who can afford a 75 grand truck care about saving fuel? Well, nobody ever got rich throwing money away. The AT4 designation is GMC’s second “sub-brand”. The first, Denali, has been phenomenally successful and aims for pure “luxury”.

The AT4 is for off-roaders, with a darker, more sinister look, bright red front and rear towbars, upgraded suspension and beefier tyres, all aimed at superior go-anywhere capability.

Review the 2020 GMC Sierra AT4

As mentioned, my tester had GM’s 3.0-liter turbodiesel engine. It’s an inline six, so it’s inherently balanced for smooth operation. It produces 277 horsepower at 3,750 rpm and a healthy 460 lb-ft of torque at a low 1,500 rpm By compression ignition standards, this engine starts quickly – 0°C. cold start took less than three seconds, faster than I could fasten my seat belt.

By the same token, it’s impressively quiet, at least from the inside. Outside is part of the characteristic Diesel shell. People will know you’re coming, but compared to my old Diesel Suburban, it’s a library in there. The good low-end torque gets you off the line quickly, and the smooth-shifting ten-speed automatic transmission means you can generally keep the revs under three grand.

Once you’re on the move, the blocky Goodyear DuraTrac all-terrain tires make more noise than the engine. The stiffer suspension also comes at a cost in ride quality, making the AT4 a bit harsh on our pockmarked roads. The electric power steering provides good feel with enough weight to know you’re actually in command.

A “Drive Mode” knob sits on the dashboard to the left of the steering wheel. Turn it to the right to successively select Normal, Sport or Off-Road settings, altering various system responses to suit.

Frankly, I didn’t detect much difference between the first two, although the gearbox does hold gears longer before upshifting in Sport. I didn’t drive the AT4 off-road, but I know from past experience that it will go places you wouldn’t think. There are also a couple of meters that show how steep and how “lean” you are.

If you turn that Drive Mode dial to the left, you get “Tow/Haul,” which calibrates things for towing a heavy trailer. This also enables control of trailer brakes and help with coupling alignment when coupling. The interior of the AT4 looks much like any big GM truck, with nice quality, readable gauges, easy-to-reach controls, and a head-up display that I could turn off. In front of the driver is the tachometer on the left, the speedometer on the right and four smaller gauges between them, for oil pressure, coolant temperature, fuel level and battery voltage.

Review the 2020 GMC Sierra AT4

Many functions can be operated via the bright, clear central screen, but many are also replicated with the right knobs or buttons. My guess is that many mountain bikers wear gloves that may not work with touchscreens.

The AT4 has all the technology you could want, and probably more, including Apple CarPlay, Android Auto, and Amazon Alexa, Sirius XM radio with a three-month free trial, USB A and C connectors, 12- and 120-volt outlets in the dash plus built-in Wi-Fi. Oddment storage is handled by a pair of open bins in the center console, a massive covered central box and two glove boxes. Two cup holders too, of course.

The seats were upholstered in perforated leather, dark gray with orange accents. These colors were picked up on the dashboard and door panels. The back seat has plenty of legroom. The seat cushions can be folded up to create a huge storage space inside; the jack and tools are also stored underneath. Panels on the back of the two outer rear seats can be opened to create out-of-sight bins for valuables such as wallets or house keys.

The front seats are heated and ventilated; the two outer rear seats are heated. There’s also a steering wheel heater (yay) but there are gaps in the coverage, especially at the “quarter to three” positions which are where your hands should be. Large grab handles are located at all four corners for ease of entry and exit and for passengers to hold onto if the driver is doing particularly athletic off-road driving.

Key among the options on my tester was the “Carbonpro” composite bed, which should stand up to some serious bashing. This may be the single largest use of carbon fiber bits offered in any volume vehicle. Looks cool too. It’s better, because it costs almost five thousand extra. The tailgate is a multi-functional affair. Its downward movement is dampened so that it opens smoothly. Press another tab and part of it can be folded down to make a step for accessing the bed. Footrests molded into the lower rear corner of the truck and a folding handle on the side of the bed further aid in getting into the box. Towbars throughout help secure your load.

Like all GM vehicles, this one fails the ignition off/headlight off test. But it passes the wing mirror test; you can adjust them far enough out to eliminate the so-called dead spots. There are a number of driver assistance features – such as lane keeping – which I usually turn off. I usually leave automatic emergency braking on. Better to have it and not need it than to need it and not have it.

Review the 2020 GMC Sierra AT4

And the back-up camera has a variety of views, including a wide angle when you have a trailer attached. There are also forward views available in certain conditions which can be helpful, especially in tricky terrain situations.

And I like GM’s reverse warning system that vibrates your seat cushion instead of beeping, so no one else in the truck knows.

The truck industry could build an entire year’s worth of vehicles and never build the exact same truck twice. So it’s impossible for a reviewer to run just one example and tell you everything you need to know. What I can tell you about the Sierra AT4 is that it’s an expensive but handsome and capable full-size truck that will go anywhere you can imagine, and more that you probably couldn’t.

The diesel engine offers excellent performance. And fuel economy – the best recorded in my truck was 7.4 liters per 100 km, which is amazing.

There are always compromises and in this case ride quality and interior noise.

If they are deal-breakers, there are plenty of options at your GMC store.

Tthe vehicle was provided to the author by the car manufacturer. Content and vehicle evaluations were not subject to e.go approval.

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