I Drove GMC's Longest-Range Electric Truck That Tows Hands-Free

I have never towed anything in my life, but somehow I've found myself hurtling down a track hauling a 20-foot, 5,600-pound trailer. And my hands aren't on the steering wheel.

Despite what you might think, this isn't reckless driving. I'm behind the wheel of the new GMC Sierra EV Denali Edition 1 pickup truck at the General Motors Proving Ground in Milford, Michigan, putting it through a series of ride and handling tests. Part of the testing includes trying Super Cruise, GM's hands-free driving system that will grow to cover over 750,000 miles of mapped roadway in the US and Canada by the end of 2025. It's the only hands-free system that also works while towing.

But driving on these test tracks is the last stop in the development process. Before rubber ever hit the road, the Sierra EV drove 17.5 million miles – virtually. GMC invited CNET to see how the vehicle was made, where I explored everything from the battery labs, to a driver in the loop simulator. Borrowed from motor racing, it lets drivers simulate what a vehicle will actually feel like on the road before the physical truck exists.

Watch this: GMC Sierra EV: I Towed 5,600 Pounds HANDS-FREE! (Exclusive Look)

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"Being able to do the virtual development helps our timeline and speeds it up," said Kathy Gillespie, vehicle chief engineer at GM as I spoke with her about the Sierra EV. Before virtual development, it might have taken anywhere between five to seven years to bring a vehicle to market.

The era of the electric pickup truck is well and truly here. Ford, Rivian, Tesla and GM all have offerings that cater to either work or adventure truck buyers. EV pickup trucks are the fastest-growing segment by fuel category in the US, according to Mordor Intelligence, even though many can cost close to $100,000 or more.

Along with the Chevrolet Silverado EV, which shares the same body and battery platform, the Sierra EV has the longest range of any electric truck so far, at a GM-estimated 440 miles. The Ford F-150 Lightning and Rivian R1T by comparison max out at 320 and 420 miles, respectively. Although the Sierra EV was originally specified to be an over-400-mile range truck, GMC was able to get 440 miles, according to Gillespie. 

I saw first-hand how some of that range was gained and how virtual tools are speeding up EV production.

Virtual reality meets EV research and development 

Almost every single element of the Sierra EV went through some element of virtual testing, from the infotainment system, to the cabin design. At GM's design center, CNET got an exclusive look at how the team used virtual reality headsets to simulate the feel of the interior before actual models were made.

I put on a headset and sat in the driver's seat of the Sierra EV, virtually. The first thing I noticed was how it feels almost exactly the same as the real truck. Everything from the door trims, to the stitching on the passenger seat looks real. So real that I almost reached out to grab the wheel.

At the start of the process, designing in VR helps designers determine if the interior proportions are right. They can map out the location of the steering wheel and infotainment systems. Once detailed surface models are rendered toward the end of the process, they can swap out finishes and colors on different elements of the trim. "It also allows us to sort of deep dive how parts fit and how you really feel in the environment," said Therese Pinazzo, director for interiors at GMC and Buick.

It sounds surprising, but despite a suite of virtual development, car companies like GM still use clay to build car models. Right below the room where we're sitting, I can see a team of designers hand-carving clay vehicles.

"We'll mill in clay, we'll scan and then we'll take them back into the head mounted display just to do checks," Pinazzo said. "But it is really possible to do all of this virtually."

A peek inside GM's battery labs

GM's battery systems lab sits in an inconspicuous building at its Warren, Michigan, campus, about an hour's drive from the Proving Ground. Like other elements in the vehicle, the majority of the battery testing is done virtually. But there are several physical, real-world tests engineers use to simulate extreme environments a vehicle might encounter. 

One chamber can heat and cool a battery pack anywhere between 68 (154 Fahrenheit) to minus 68 degrees Celsius (minus 90 degrees Fahrenheit), which helps to test power deviations when the cells cool. One of the engineers opens the door and I'm hit by a cloud of freezing cold air. The pack stays in there for weeks on end to simulate performance during a prolonged cold snap.

Down the hall is the mega shaker, a giant machine that can replicate bumps and vibrations at speed to test battery pack performance. "If you're going down a highway, you're trying to simulate a two inch bump at 60 mph, you're doing 60Hz a second – that's a lot of inertia to control," said Eric Boor, senior leader at the battery lab.

To get an estimated 440 miles range out of the Sierra EV's largest battery pack, modifications were made to the battery cell so it could get heat out more efficiently. A pouch wraps around the electrodes, which makes it easier to get heat out compared with earlier cells. It's "kind of like a taco," said Andy Oury, chief of staff to the vice president of batteries, as he showed me one of the cells up close.

This "taco" design also helped reduce space at the bottom of the cell by about two millimeters. It doesn't sound like much, but on a 100-millimeter-tall cell, that's about 2% extra height, Oury said. "You could think of that as almost 2% extra range in your vehicle." 

The battery pack is also capable of up to 350-kilowatt charging at a DC fast charge station, which can give the Sierra EV up to 100 miles of range in 10 minutes. During a power outage, the Sierra EV can power your house with vehicle to home, or V2H. This will also be standard on all GM EVs using the Ultium platform by 2026. A limited number of EVs from other manufacturers also offer bidirectional charging.

Simulators test vehicles before they're even built

Back at the Proving Ground, I'm sitting in a darkened room, behind the wheel of a driver-in-the-loop simulator. It feels like a fancy racing simulator in an arcade, as it's raised up off the ground and has 6 degrees of freedom. Drivers can ride on mapped roads from all over the world, giving feedback on steering, suspension and other drive metrics used to tune the vehicle. 

There's a 180-degree wraparound screen that shows a view of the road, from the streets surrounding Milford, to the famous Nürburgring racing complex in Germany. "It simulates any road surface," Gillespie said. "You can do a lot of that tuning before you ever get wheels on the road." 

Virtual testing also extends to components like braking and steering, which have their own setups in another lab across the hall. All the brake hardware, including controllers, calipers and hoses are physically here, but engineers can input and simulate the rest of the truck elements to see how they perform and interact, before the vehicle exists. "We can do all of that testing and all of that development work [in] real time, 24 hours a day," Gillespie said.

This is also where engineers do validation testing for specific EV elements like one -pedal drive, which would normally take a driver days or weeks in the real world. In the lab, it takes only between 30 and 50 hours.

I also get to sit in the passenger seat of a Sierra EV to see how engineers test road forces on the vehicle. Each tire sits on a hydraulic post that simulates different road environments, but the vehicle isn't actually driving. During one test, if I closed my eyes I could swear we were driving over railroad tracks, even though I knew the truck wasn't actually on the road.

Real world test driving (not virtual) 

Not many people outside of GM employees and test drivers get to experience the ride and handling loops at the Proving Ground. Complete with potholes, railroad tracks and ditches, the tracks simulate all sorts of real-world driving conditions. There's also the circle track that looks exactly like you'd imagine -- a giant circle. 

It's here where I get to try out Super Cruise while trailering, which is deceptively easy to use. All you do is center the truck in a lane on a mapped road and press the Super Cruise button on the steering wheel. A light bar on the steering wheel will turn green and then you can take your hands off the wheel. There's a camera sensor that makes sure you keep your eyes on the road and will alert you if it detects you're not paying attention.

The first time I turned on Super Cruise, I screamed. It didn't really feel like I was towing anything to begin with, but doing it hands-free was even more surreal. You can see more of the test tracks and the Proving Ground experience in the video on this page.

While virtual driving now makes up the bulk of the testing process, the Sierra EV also went through nearly 1 million miles of real-world driving before hitting production.

After two days of seeing how GMC built and tested the Sierra EV Denali Edition 1, what struck me the most was how much it just felt like a truck at heart, despite all the technology and virtual development that went into it. 

"At the end of the day, it's a truck, and it's got to do the same things that any other truck would," said Mike Kirbitz, motions controls lead for Sierra EV. "So you develop it to the same criteria."