Video: How Does The 2021 GMC Sierra 1500 AT4 Diesel Handle the Mountains in Winter Conditions?

2021 gmc siera 1500 at4 diesel duramax

Some of us adore the 2021 GMC Sierra 1500 AT4 diesel and wanted to push it hard – in the snow.

Ironclads Trail is tough enough on its own, but when you include snow, it will be a hell of a challenge for the 2021 GMC Sierra 1500 AT4 diesel. The GMC Sierra AT4 we’re testing has already acquired accolades from the TFL Studios’ team for its excellent drivability, economy, smoothness, and utility. Had we not blown our budget on testosterone-heavy vehicles like the Raptor and TRX, we would beg the boss to get an AT4.

One of the best parts of our AT4 tester has to be its 3.0-liter Duramax diesel.

  • 277 hp @ 3750 rpm
  • 460 lb-ft of torque @ 1500 rpm
  • 10-speed automatic transmission
  • Includes diesel exhaust brake

Additional AT4 upgrades:

  • Skid plates
  • 3.23 rear axle ratio and Monotube Rancho® shocks
  • The suspension package adds about 2-inches of ground clearance
  • This lift improves approach and departure angles
  • Goodyear Wrangler Duratrac M+S tires
  • Hill Descent control

One issue:

There is one bone of contention with this otherwise brilliant truck. None of us are pleased with the performance of the G80 rear-locking differential. It is mechanical and has been a mainstay for GM half-ton trucks for years. On the road, and in slippery conditions, the G80 works well enough. When one rear wheel slips, the rear-end (eventually) locks up allowing both rear wheels to acquire an equal amount of torque. Simply put: it locks up the rear end when one wheel slips.

Unfortunately, that slippage can be detrimental on the trail. Our long-term Chevrolet Silverado 1500 Trail Boss also has a G80, and we tested it thoroughly off-road. The traction loss held back what was otherwise an outstanding trail truck. Same thing with the AT4. Out of five half-ton truck-builders selling in the U.S. – only GM and Toyota refuse to offer a driver-actuated rear locker of some kind.

You can read about this same truck being tested on snowy streets (here),

… and other goodies:

  • CarbonPro (Carbon Composite) Bed
  • GMC MultiPro Tailgate
  • Over a dozen configurable camera views

This is an expensive pickup truck – especially for a half-ton. A base model GMC Sierra 1500 AT4 starts at about $56,000. The MSRP on our fully-loaded AT4 is $64,850. Yes, that’s a lot of money, but it is comparable to other trucks in the same class with small-displacement diesel engines. In fact, the equivalent 2021 Ford F-150 Platinum (with the diesel and FX4 package) runs about $69,000.

In this video, Andre pushes the AT4 in a difficult, snowy off-road area. He gets to show us exactly what the truck can do on surfaces that most pickup trucks do not like to play on. On top of that, he gives us technical details about the AT4 to boot.

Easily amused by anything with four wheels, Nathan Adlen reviews vehicles from the cheapest to the most prestigious. Wrecking yards, dealer lots, garages, racetracks, professional automotive testing and automotive journalism - Nathan has experienced a wide range of the automotive spectrum. Brought up in the California car culture and educated in theater, childhood education, film, journalism and history, Nathan now lives with his family in Denver, CO. His words, good humor and video are enjoyed worldwide.