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So Much for the Cornfield Cadillac

Posted: August 1, 2014 by Jim Park

International promised ProStar would be a huge leap forward in truck design and they’ve delivered. Along with a number of essentially new design elements, there’s a lengthy list of substantial improvements to existing technology and hardware. The maintenance and service tasks have been significantly streamlined and simplified through a series of well-thought-out design changes, and ProStar’s driver environment is the best I’ve ever seen in an International product.

All this is the result of some serious research into the day-to-day operation of the truck, and what it takes to keep drivers comfortable and happy.

Lets start with the “new and improved” list. The front bumper is designed to tip forward and drop out of the driver’s or tech’s way to improve access to the engine compartment. And moving it is a really simple task. Undo two latches, and the bumper drops out of the way.

“We’ve had really positive feedback on that,” says International’s Jodi Presswood, the company’s Heavy Product Center Program Manager.
“Especially from the maintainers. It requires no tools, it’s quick and easy, and there’s no need to jump over the bumper or cut the wheels to get at the engine. We’ve had questions too about the durability of the cables, but we’ve tested multiple samples through thousands of cycles and free drops with no problems at all.”

It looks like a two-piece bumper, but it’s actually four. There’s a split down the middle for both the inner structural piece and the outer piece.
Some impact may damage the outer piece, but not the inner, so you’d only have to replace the outer section on one side.

Under the hood, you’ll find translucent fluid containers for easy fluid-level checks, a proprietary oil-filler cap that has a built-in funnel, a no-mess radiator drain tube, tool-less replacement of the air filter, and more. The fan shroud is a two-piece affair with the top section easily removable for fan or fan drive service.

A lot of work was done to improve the ride quality in ProStar as well as reducing in-cab noise levels. A new sleeper mounting system features an air-over-strut design — the strut takes out the side-to-side and fore-and-aft movement, while the airbag handles the vertical loads — mounted are well outboard of the frame for improved lateral stability.

The ISX sits low in the frame and it’s tucked back
under the cab to keep the hood profile as low as possible.

The styling lines that run along the side of the truck and kick up across the sleeper side panels are not just aesthetic. They help stiffen the side panels to keep engine, road and wind noise out of the cab.

The insulation is still only R3, but it’s applied pretty evenly under the cab skin, helping to deaden the outside noise. The thick floor covering helps here, too.

International arranged a terrific test drive for me and Steve Sturgess, editor of the American driver-based magazine roadSTAR, in late May. We both came away very pleased with the truck. Improvements in hardware and design are fine, but if they don’t work in the real world, what have you really got? ProStar works.

Sturgess and I put over 1,200 miles on the truck, jumping into it at Ontario, California, and dropping it at Jim Hebe’s dealership in Tacoma, Wash. We ran I-5 up to Weed, then grabbed US 97, which took us through Bend and Biggs, Ore. Then, it was west to Portland on I-84, and north on I-5 to Tacoma.

Heat, stiff head winds, and crummy interstates plagued us in the Golden State, while some twisty, hilly two and four-lane roads made the Oregon portion of the trip an absolute pleasure.

If I had to sum up the most dramatic improvement in ProStar it’s the quiet. ProStar significantly bettered the previous record holder, Volvo’s VN, at 70dB on the sound meter at cruise, but ProStar came in at 66dB at cruise. For reference, my Taurus runs 58dB at cruise. Under a load at 1,300 rpm, it registered 68db — same as with the engine brake on. It’s worth noting here that Freightliner’s Cascadia is neck-and-neck with ProStar, according to Sturgess’ meter and mine.

A flip up wardrobe on the rear wall turns
useless space into valuable storage space.

The DPF kills a lot of the engine brake bark, while a terrific sealing package around the windows, door, and the shift lever takes care of a lot of the road and engine noise.

Many miles of California’s badly ribbed I-5 are downright rotten to drive on, but I give ProStar’s cab and chassis suspension high marks for taking the jolt out of the pavement separations. It was still bumpy, mind you, but not as jarring as I expected.

ProStar scores high in my mind on driver position and the whole ergonomics thing. The main control inputs and principle gauges are easy to use, but I had to crane my neck to see a few of the less important instruments.

The very adjustable steering wheel has integrated controls for the cruise, engine-brake, marker and headlight interrupter switches, as well as the horns (air and electric), and the radio volume and tuner.

Access to storage for stuff like maps, cigarettes, and your log book are all easy to reach from the driver’s perch, and there’s a pair of nice cup holders and a perfectly placed ashtray for those who still indulge.

Clearly, some thought went into the cab setup. But, the gear shift needs some work, I think. Spec ProStar with an automated transmission and the problem disappears, but with the manual stick, it’s a little hard to reach the far-right gear slots. Also, the stick is as crooked as a dog’s hind leg. It could, I think, be straightened, and tipped a little closer to the driver’s right hand.

According to the vehicle information display (standard on the Limited edition trim level, an option on others), we averaged 5.9 mpg for the trip. The truck had less than 3,000 miles on it when we got it, and we pulled a ­relatively light load at 65,000 GVW.

Still, I thought the headwinds between Los Angeles and Sacramento might have had a more damaging impact on our fuel economy. Sturgess and I stuck to the ­posted speed limits — mostly — and made a conscious effort to drive it efficiently.

The 485-hp/1,650-lb-ft ISX was a nice match for the work we did. Its modest power rating ensures decent fuel economy, but it’s still up to the task of moving freight through the mountains. Of course the engine gets a bit of a break from ProStar’s sleek outer profile.

International claims ProStar produces something like 9.4-percent less drag than its closest competitor (whichever truck that is), and offers more than four percent in fuel savings.

Numbers are numbers, but just looking at it you can see where the aerodynamic shape would cut the wind pretty effectively. They’ve done a terrific job on improving air flow under, over, and around the truck, and the utter lack of wind noise — even in a crosswind — tells you it’s as easy on fuel as it is on the ears.

Drivers of all stripes are bound to like ProStar, even the die-hard 9900 fans will come around soon enough, I predict. There’s too much to like about this truck to dismiss it as “not my style.” Beyond comfort, space, style and driveability, it’s an easier truck to maintain.

It’s designed with serviceability in mind, and the synchronized service intervals will require 59 fewer visits to the shop for routine maintenance — International claims — over its life span. It’ll ultimately be a more productive truck.


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