2020 GMC Sierra Heavy Duty First Drive Review: A Tech And Towing Monster

The arms race in the truck segment is all about towing capability, not necessarily engine size. Horsepower isn't getting weight moving and if the torque isn't delivered in the right place then pulling something becomes a laborious affair. If the heat generated under exertion by the engine isn't dealt with properly, then you won't be towing your huge payload for long. While there is a gigantic 6.6-liter gas-powered engine option for the Sierra HD, the maximum towing ability of over 30,000 lbs is all down to the Duramax 6.6L turbo-diesel engine under the hood that's mated to a 10-speed Allison transmission.

It was the Duramax vehicles we drove in Wyoming and got plenty of time behind the wheel towing long trailers, heavy trailers, and no trailers. Even towing the trailer loaded with 30,000 lbs of heavy metal, the Duramax engine didn't feel strained and was a testament to the 910 lb-ft of torque being delivered at just 1,600 rpm. The diesel engine isn't noisy either and, even with a load, it was easy to forget it's a diesel lump under the hood. The only intrusive noise comes occasionally under acceleration and directly from the new dual-path air intake added to the Duramax engine to increase cooling ability.

The interior design is one of the few places the HD trucks disappointed. GMC was eager to point out its aim is to be a premium truck builder, but the interior here is heavily weighted on the side of function over form. That function is great though, with plenty of room for everyone in the crew-cab and everything easily in reach along with a plethora of charging options for electronics as well as 120-volt outlets conveniently placed. But the style expected from something billed as being premium just isn't there. That's not to say we are down on the interior, it is a truck after all and GMC has put a lot of thought into the technology in the cab.

GMC's infotainment system is quick to respond and navigation is simple and intuitive through the 8-inch touchscreen. Apple Carplay and Android Auto are standard. The 15-inch head-up display shines in its visibility and usefulness as does the rear camera mirror that lets you see what's going on behind you when you have a tall load in the back.

Where GMC knocks it out of the park with technology though is the camera views you can use via the screen for towing. A six-camera setup is standard, but an extra two can be added by the dealer to go inside and at the rear of the trailer. In total, you can have 15 different views to see what's going on around and behind the trailer. Most useful is the dual-view looking backwards down each side of the trailer at the same time, and the almost magical invisible trailer view. The invisible trailer view uses the accessory camera at the back of the trailer in conjunction with the tailgate-mounted trailer to "see" through the trailer and get a clear view of the traffic mounting up behind you on a mountain pass.

Added to that is the MyGMC app that gives a quick and convenient way of checking off the provided trailer hitching checklist before heading off on a towing mission. It gives access to things like the individual tire pressures and temperature as well as the ability to check the trailer's taillights and the propane, water, and grey/black water levels. It will even take control of the HVAC system so a camper can be cooled or warmed just before reaching the destination.

The Duramax engine and Allison transmission combo is a truly glorious meeting of engineering. The torque comes early so pulling a big load out of a junction is not, as we found out with a 40-foot RV weighing around 13,000 lbs, as stressful as it could be. Getting up to cruising speed is a smooth transition from the initial pull. Even maintaining an even speed on downward grades was easy enough with the exhaust braking system and Tow/Haul mode turned on. The biggest issue to overcome when towing using GMC's setup was remembering we had all that weight pushing us when it came time to slow down. Even with the 30,000 lb trailer hooked up, towing was comfortable despite there being many times the weight of the truck pushing against us when coming to a stop.

With or without something to tow, GMC's decision to go with independent front suspension helps keep the ride smooth and almost SUV like. Off the tarmac and on tracks running around farmers fields with a payload of logs, the Sierra HD equipped with the new AT4 off-road trim feels like an SUV, although without the payload we suspect the solid-rear axle would be the giveaway that you're in a truck.

The GMC Sierra HD is not inexpensive. The base price is $40,000, plus a $1,594 destination charge, and adding the diesel engine to the base trim costs an extra $9,000. Most GMC customers though will want to go with either the premium Denali trim or the off-road AT4 trim that features off-road suspension, Rancho Shocks, skid plates, an Eaton locking rear differential, traction select system with specific off-road mode, hill descent control, hill start assist, the 15-inch diagonal head-up display with off-road inclinometer, and HD Surround Vision1 for low-speed views of vehicle surroundings.

Denali trim starts at $63,700 while the AT4 starts at $57,700. The trucks we drove in Wyoming with their technology upgrades were all priced close to $80,000. While this is not cheap, when we consider the sheer amount of upgrades over the outgoing model it's hard to argue the there isn't strong value being given for the money.

GMC's approach of integrating the trailer and the truck rather than treating a trailer as an addition to the truck certainly pays off. The engineering team playfully claimed to us that 57% of people they've talked to say towing is stressful, and the rest are lying. However, the engineering team is dead serious about taking that stress out of towing. It's hard not to be impressed at the result as we didn't just comfortably tow various trailers around, but also did it at altitude and close to maximum weight.

We will have to wait until we can spend some quality time with the Sierra HD on a larger selection of roads and doing other truck things to get a full sense of what it's like to live with, but in terms of performance and technology GMC is shaping up well to hit a home run with the new Sierra HD.