Test Unit Specs
Tractor Weight (dry): 18,370 lbs.
Wheelbase: 273 inches
BBC: 131 inches
Engine: Cummins ISX, rated at 550 hp
Transmission: Fuller RTLO20918B
Clutch: Eaton Fuller 15.5 ceramic
Front Axle: Dana E1202W, rated at 12,000 lbs.
Rear Axle: Dana DSH40, rated at 40,000 lbs.
Rear Axle Ratio: 3.70
Front: Bridgestone R287, 295/75R22.5
Rear: Bridgestone M726EL, 295/75R22.5
Wheels: Peterbilt 22.5 X 8.25 polished aluminum
Brakes: 16.5 X 7 cam
Front: Bendix lube-free disc
Rear: 16.5 X 7 cam
Front: Taper Leaf
Rear: Peterbilt Low Air Leaf
Turning Diameter Right: 36.2 ft.
Turning Diameter Left: 43.4 ft.
Fifth Wheel: Holland, with 36.7-inch air-operated slide
Steering: TRW TAS65
Fuel Capacity: Twin 150-gallon tanks
Other Items: Hogebuilt stainless steel quarter fenders, remote keyless entry, Platinum interior package, 70-inch Ultracab sleeper, Sirius satellite radio, Peterbilt navigation system, Denso 130-amp alternator, Mitsubishi starter
The more things change, the more they stay the same. In the world of trucking, no product better demonstrates the truth in that adage than the Peterbilt Model 389, introduced at the Mid-America Trucking Show last March and available as of last month.
Roughly 99.27 percent of the Model 389 is composed of parts taken directly from its soon-to-be predecessor, the Model 379, a legendary truck that’s been in production for 20 years and relatively unchanged during that time. The 379 itself was somewhat of a clone, an upgraded version of the Model 359, which had been Peterbilt’s flagship vehicle between 1966 and ’86.
Despite – or maybe because of – a stylistic lineage that dates back to the Johnson Administration, the Model 379 has long been a favorite of owner-operators enamored with traditional squarish hoods, big West Coast bumpers and smaller (i.e., “cozy”) cabs. The trucks’ resale prices, always atop the charts, bear out their ongoing popularity among those who value aesthetics over aerodynamics.
Given this impressive level and length of marketing success, one might reasonably wonder why Pete officials would retire the 379 – ever. Scott Newhouse, assistant chief engineer for Peterbilt, says the decision started with the changes needed to comply with the Environmental Protection Agency’s diesel emission mandates for 2007.
“A few years ago, when we learned about the heat-rejection requirements of the ’07 engines, we knew that we’d need a new cooling system and improved airflow under the hood,” he says. “We looked at this as an opportunity to give our customers something extra – not simply add equipment, weight and cost – to make the trucks compliant with the new rules. We focused on areas that would add value, to help fuel economy and boost driver comfort and productivity. That’s what really drove these latest improvements.”
The 389 is, at first glance, a 379 with Calvin-Klein-like headlights. Looking closer, though, Pete enthusiasts will notice that the hood is longer, the grille crown is slightly beveled with larger corner radii, the sun visor is contoured, the grille and air cleaner screens feature a punched oval pattern (first used on the Model 379X, introduced in 2003), the hood ornament is more streamlined, and the front edges of the tool and battery boxes have rounded fronts. Inside, a Peterbilt-specific driver information display and Lowrance-made touch-screen GPS unit occupy space in the dashboard’s A and B panels (respectively).
I recently had an opportunity to test drive a 389 on a short lap of rural Texas, from Denton to Sherman to Greenville and back to Denton. My route, across terrain as flat as Nebraska, was no challenge for the 550-horsepower Cummins ISX under the hood, nor did it provide any logical reason to put the Fuller 18-speed through all of its ratios – even though the truck was loaded to nearly the legal limit. Some stretches of the mostly two-lane path I followed, however, did provide a good demonstration of the chassis and cab suspensions. Together, they delivered a ride that was firm yet comfortable. I’d describe it as a classic Peterbilt feel, which is neither harsh nor mushy.
As someone who doesn’t truck on a daily basis, I spent the first 40 or 50 miles of my test drive getting accustomed to that vast aluminum acreage directly ahead of the windshield. If it’s true that length matters, the 389 now offers drivers four more inches to brag about. This added space, boosting the BBC from 127 to 131 inches, was apparently necessary to accommodate the various emissions components required on trucks built after Jan. 1. Truckers wanting a somewhat shorter, traditionally styled Pete will have to settle for the Model 388, whose BBC spans a mere 123 inches. The extended hood on the 389 will certainly be popular with “large car” aficionados of all stripes. Although it makes a bold vehicular statement, it also obscures sight of the road for the first 34 feet in front of the bumper – this without a bug deflector mounted to the grille crown.
Surprisingly, the 389’s mammoth snout tips with little effort. Peterbilt’s Newhouse says that engineers redesigned the hood’s spring geometry to make opening and closing as easy as possible. They also added a locking mechanism – first deployed last year on the Model 386 – to secure the hood in its open position, which is now a full 90 degrees from closed.
My relatively short trip in the fire-engine-red 389 began and ended during daylight hours. As a result, I was unable to observe the newly designed headlamps in action. According to the truck’s makers, the pair “increases light on the road by a whoppin’ 226 percent over previous sealed-beam designs.” Newhouse says the effect is similar to that of HID (high intensity discharge) lighting used on some European cars.
“We’re still using halogen bulbs,” he says, “but our designers have fine-tuned the lens optics to throw more light that’s crisper, or whiter, than we’ve had in the past. The better quality of illumination will reduce strain on drivers’ eyes.”
Owners who opt for the factory-installed GPS unit will also experience less emotional strain. I became dependent on the device within an hour of starting my journey, constantly checking it for the names of upcoming towns and crossroads long before their roadside signs came into view. Like all other such units, this one will either track the vehicle’s movement or display real-time directions to a destination. It is also programmable to include repeat routes and favorite stops, such as a Waffle House or factory-outlet mall. Equally important, it’s easy to view, mounted in the middle of the B panel, and reasonably simple to operate, using touch-screen commands.
Complementing the GPS unit is a new proprietary driver information display, located above the speedometer and tach on the dash’s A panel. This digital readout shows numerous current and historic stats on the truck’s operation, from fuel economy to trip length to engine conditions to service intervals and much, much more. Some of the display’s numerous menus are deactivated when the truck is moving.
I would have used the system to monitor fuel mileage except that I was at the helm of a preproduction model suffering from some algorithmic sniffles. Had everything been working properly, though, I probably wouldn’t have impressed anyone with my mpg because I’d mistakenly chosen routes notable only for their stoplights, thick traffic and 90-degree corners.
It’s difficult to accurately predict how efficiently the 389 will run on a sparsely populated freeway. The truck will never get into the Guinness book for its aerodynamic shape. Still, it is slightly (2.4 percent) “slipperier” than the 379. In theory, this improvement should translate into a 1.2 percent fuel economy gain. Unfortunately, these trucks will be powered by ’07 engines designed to burn ultra-low-sulfur diesel, a fuel with supposedly 1 mpg less combustible oomph than that of the previous variety.
But this might all be academic gibberish to actual buyers. They’re not choosing a square hood for its ability to cleanly slice through the wind. They’re seeking gratification, the sort derived from running equipment that turns heads and generates pride and envy.
Since the mid-’60s, Peterbilt executives have recognized the allure of their premium owner-operator models, the 359 and 379. They’ve done well during the past four decades, updating the trucks incrementally to stay current with technology and driver comfort while maintaining an unapologetic traditional style. Now the corporate hopes hang on the 389, which is more refined than, yet much the same as, its iconic forbearers.
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