Fans of Peterbilt’s venerable Model 379 will not be disappointed with its successor, the Model 389. It’s much the same truck, only better. All that you like about the Model 379 is very much in evidence on the 389, but now, the ride is better, the hood is even longer, it turns tighter, and it takes a little less of a bite out of the wind. Some will like the new headlight style, some won’t, but few who try them will disagree that they cast a whiter beam of light farther down the road, and that can’t be bad for anyone. I was anxious to see if the modifications made to the 389 in fitting up the 2007 engines would compromise the truck in any way, so when the invitation came from Derek Smith, Peterbilt’s marketing communications manager, I was quick to say yes to the ride he was offering. The short answer is the truck is better for the change. The long answer, which follows, is the 389 retains all that’s good about the 379, while making the best of the chassis modifications required to accommodate the new engine and emissions control hardware. The only downside is Canadian buyers wanting a 389 long-hood model — now listed as 131-in. BBC — will be limited to a 63-in. sleeper because of our archaic vehicle length restrictions. Customers may opt for the shorter BBC Model 388 to retain the larger sleeper option. It’s Cool With the hood open, you’ll wonder why they had to stretch the BBC length to 131 in. There’s loads of room between the engine and the firewall, and the cooling package isn’t dramatically larger. It’s three inches wider, in fact, and 60 lb lighter too, but Scott Newhouse, Peterbilt’s assistant chief engineer, told me it’s all about air flow. “The cooling system itself is more efficient for 2007,” he said. “We got closer tolerances between the fan tips and the engine-mounted fan shroud, and the shroud itself is isolated from the cooling module by a flexible rubber boot. We’re pulling all the air we need through the rad now, but we needed the extra length to optimize air flow through the engine compartment.” It was unseasonably hot and humid the weekend I drove the truck around east Texas, but I don’t recall the coolant temp getting much above 200° F at any time, so the system must be working. I experienced a fair bit of fan-on time, but that was mostly due to the air conditioning operation. The longer hood allowed engineers to make an interesting enhancement to the front suspension, too. The long 71-in. front springs provided a real smooth ride, but because the axle is set as far forward as it can be on the springs — I’d estimate 3/5 of the way forward — there’s virtually no sway to the front end. The short distance between the front pins and the axle keeps everything nice and stiff for terrific handling. They’ve also managed to carve 48 in. out of the curb-to-curb turning radius, pretty well offsetting any maneuverability issues associated with the 273-in. wheelbase. Where’s the DPF? The diesel particulate filters required on all 2007 engines have created some placement challenges for truck makers. They’re generally only slightly bigger than a typical muffler, but they need to be mounted close to the turbocharger so that the internal temperatures can be kept high enough to facilitate passive regeneration of the particulate filter. Peterbilt has placed the Cummins DPF under the passenger door, hidden behind the tool box. There’s still a flip-open door on the tool box, though with a little less space in the box, but the trade-off for DPF placement ought to result in fewer fuel-consuming active regen events. The DPF has dual outlets for twin stacks. It would be difficult to report on the DPF performance because I’ve got nothing to compare it to, but in the 600 or so miles I put on the truck — mostly on two-lane roads and through a fair bit of stop-and-go traffic in that damned Dallas rush hour — it never once cycled into regen mode.
Built-in GPS Peterbilt is now offering an in-dash GPS navigation system, and I have to say it’s pretty slick. It talked me through the directions, reminding me when to turn, etc. It’s pre-loaded with truckstop and Peterbilt dealership coordinates, among other way points — and you can add way points of your own too. It’s pretty easy to navigate to where you want to be, if you know where you want to go. A word of caution here, though: be careful what you ask for ’cause you just might get it. I inadvertently selected the wrong truckstop from the menu, the GPS plotted the course, and away we went. It was a few miles before I realized my error and got us reprogrammed. Steering and Gearing Current owners of a 379 will be pleased with what Peterbilt has done to the truck for 2007. Most notable, I’d say, is the improved ride and handling. The longer front springs and the forward placement of the axle makes quite a difference to the way it feels on the road. It’s more surefooted, and sways less, even in a stiff crosswind. This was more in evidence on the high-crowned two-lanes I covered. I ran east from Denton to Longview, and then south on Highway 259/59 to Houston. From there, I flipped north again on I-45 back to Denton. It was horrendously windy for most of the trip, and the crosswinds would have made for an unpleasant ride in a lesser truck. I never felt I had to hang on to this one to keep it straight. And it’s quite maneuverable too, given the length of the thing. This one had disc brakes on the front wheels, and that might have added to the cut of the wheels. I had no difficulty wheeling around the small side streets of Tyler, Nacogdoches, or Lufkin. At night, the new Pete headlights showed their worth, and even if you find them a little hard to look at, you won’t object to how well they work. Clearly, a terrific step forward in lighting technology. The Cummins ISX engine is a fairly quiet machine to begin with, and I’m happy to report, it’s taken the in-cab noise level down a couple of notches. I heard a little gear while at idle, and under power, mostly just a rumble. Absent is the loud sucking sound from the big chrome air cleaners I’ve heard on some occasions, so running with the windows down is a more pleasant experience. It would be tough to try to analyze the 389 any further. The obvious target for comparison is its predecessor — a fine ride in its own right. So, with the design changes the engineers made to accommodate the 2007 engines and the exhaust aftertreatment technology — the DPF — the 389 is much the same as the 379. Only, there’s more of it — four more inches of hood, some new electronics you’ll never have to worry about, and some clever improvements in the steering geometry and front suspension works. I like it, but that’s hardly a surprise. H
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