Peterbilt Motor Co. has followed up on the virtual launch of its new medium-duty truck launch with a chance for North America trucking journalists to see the trucks first-hand and spend some time behind the wheel of the new models to see for themselves how the Denton, Texas, truck OEM has rethought its approach to both medium-duty and vocational trucks.

At the Texas Motor Speedway outside of Dallas on April 21, 2021, Peterbilt hosted a day of briefings, walk-arounds and drives in the new models, which cover Classes 5 through 8. The models include the new Model 535 and Model 536 trucks, which are designed for the Class 5/6 non-CDL lease and rental markets, and the Model 537 and Model 548 trucks, designed for the Class 7 and 8 segments.

Power options for the new trucks are focused on the latest versions of the PX family of diesel engines, built by Peterbilt’s parent company, Paccar. These include both the PX-7 and PX-9 engines, both of which feature longer oil and fuel filter service intervals and fuel economy improvements. The updated PX-9 also logs higher torque ratings in the 260, 350 and 360 horsepower versions as well as a lower torque drop-off speed.

In another major advancement, Paccar has also introduced a brand-new, vocationally focused automatic transmission for the new medium duty lineup. Designed by ZF with a long history in Europe and Asia, the new Paccar TX-8 is a fully automatic transmission (equipped with a torque convertor) featuring eight gears and the ability to monitor changes in road grade, vehicle acceleration, torque demand, weight and engine load to keep the truck in the most fuel-efficient gear. The transmission delivers automotive-like shifting with up to 5% better fuel economy, according to Phil Hall, medium duty product manager for Peterbilt, who also notes that the new transmission features an Auto Park Lock safety system that automatically engages the park lock should a driver forget. Also, a Twin Torsional Damper enables early first gear lock-up for smoother shifts and faster acceleration.

An All-Intuitive Interior

Hall presented an overview of the new trucks before turning journalists loose on the Grand Prix course at the Texas Motor Speedway to see for themselves how his engineering team created this new medium duty lineup in a way that he called a “total rethink” for Peterbilt.

“These new trucks are a clean-sheet design,” Hall said. “We understand that the medium-duty market – and our customers who use these trucks – are changing. To meet these changing expectations and ways of working, our team settled on a ‘human-centered design.’”

Hall said that in 1995, when Peterbilt delivered its last generation of medium-duty trucks, the company was focused on “quantitative” design process. “For this new medium-duty lineup, I challenged our design team to think in terms of a ‘qualitative’ engineering process,” Hall explained. “This meant focusing on customer need and understanding why they do things in certain ways when they’re using our trucks.”

To accomplish this goal, Hall’s team met with hundreds of fleet owners and drivers to obtain key insights on how they work today – and how they believe they will be working in the future. This approach led to what Hall calls an “all-intuitive interior.” Both fleet owners and drivers helped his design team with every aspect of cab interior of the new trucks – from the placement of dials, switches and gauges to the “massive” amount and location of storage space in the cabs.

The end result, Hall says, is that while the new Peterbilt medium-duty trucks are packed with new technology, his team – and that vital customer and driver input – insured that technology serves a purpose in helping them work safer and more efficiently day in, and day out.

“Outside the truck, daily maintenance and fluid checks are in easy access points for quick and easy checks,” Hall said. “And it only takes five minutes to change out a headlight on the trucks. Inside the trucks, ergonomics dictated everything we did – from getting in, and out of the vehicles, to the haptics on the new display screen and other controls, to the advanced safety systems and how they perform to keep drivers safe on the road. And that’s why we feel this new model lineup will set a new standard for medium-duty trucks in North America – not just for the first life cycle, for multiple life cycles as they age.”

Simple, Yet Innovative Safety Features

For my first-impression test drives around the Texas Motor Speedway Grand Prix track, Peterbilt assembled all of the medium duty models spanning Classes 5 through 8, with an assortment of Model 535 and 536 trucks to choose from.

Opening the door to a red, stake-bodied Model 536, the first thing that jumped out at me was the cab interior, which is noticeably wide and airy, with excellent views over the sharply-slanted nose and out to the sides. The new, 7-inch graphic display screen in the center dash cluster was also impressive, with brilliant, infinitely adjustable, graphics and gauges. The design is matte-finished and coated to protect against glare and easy to set and scan while on the road.

Hall said his design team spent a lot of time keeping ambient noise levels low inside the new cabs, and their work was apparent when I fired up the PX-7 diesel engine up front and allowed it to settle into idle. There’s remarkably little exterior noise filtering through to the inside of the truck. Conversations with passengers don’t require any yelling and outside shouts, warnings and commands can easily be heard and understood even with the big Paccar diesel rumbling away up front.

Out on the road I was impressed with just how nimble the big Model 536 was, racking the truck effortlessly through the twists and turns on the Grand Prix course with minimal steering effort. The truck tracks perfectly with minimal steering effort, brakes well and has plenty of low-end power on hand for quick acceleration. Cruise-speed distances were limited, of course, due to the track layout. But the truck is remarkably smooth and quiet at near-highway speeds and with excellent brake response when it’s time to check up and enter a curve.

Moving down into a Class 5 Model 535 with Hall riding shotgun in the passenger seat highlighted the new passenger car feel he and his team worked so hard to instill in these new trucks. At times, the truck felt more like a big, even luxurious, SUV than a work truck, with excellent acceleration from the Paccar PX-7, and silky-smooth shifts from the new TX-8 automatic transmission. Steering inputs are indeed car-like, with the truck snaking effortlessly through the road course, with impressive braking and acceleration characteristics.

As on the Model 536, the cab is roomy and well-it, and there are numerous little storage nook and crannies within easy reach, including an innovative storage bin underneath the passenger-side seat that can be easily accessed from ground level.

There was one little touch inside the cab that I felt truly showcased how much thought Peterbilt engineers put into these new trucks – on that was inspired by Hall, himself. It’s a simple, rectangular, cell phone storage nook positioned in the center dashboard. The nook design, based on Hall’s personal experiences in his own vehicles trying to keep a cell phone positioned so that he can easily view maps while driving, was created to hold a smart phone securely in place in a horizontal position. This way, drivers can quickly and safety check directions on progress on a map app without having to constantly grab, retrieve or reposition the phone while driving. It’s very cool, but simple, feature – and one that I suspect will be greatly appreciated by busy drivers striving to be safe, yet efficient in unfamiliar surroundings and in heavy traffic.

The timing couldn’t be better for Peterbilt new medium-duty lineup as the vaccines roll out during the COVID-19 pandemic and President Biden advocates for a transformative infrastructure bill.The new trucks take full advantage of new technology in a smart, transformative way that both fleets and drivers alike will find safer, more comfortable and more efficient as traffic, freight and construction work all ramp up in the near future.