International believes it has found the answer to improved fuel economy in the sleek aerodynamic form of its new ProStar series of heavy duty trucks, which will be produced at its Chatham, Ont., assembly plant.

Aerodynamic drag can account for up to 50% of fuel efficiency when a truck is travelling at 65 mph and the truck maker meticulously collected data tables for every component on the ProStar that faced the wind – from mirrors to skirts – to first understand and then moderate the impact on drag. Much of the testing was conducted at the National Research Canada full-scale wind tunnel facility near Ottawa.

“Fuel economy is big money. Every tenth of a percentage point saved is a big deal. We think we have the best in class,” said Tom Baughman, vice president and general manager, Heavy Truck Group, International Truck and Engine Corp. when the trade press was provided with a sneak peek of the new vehicle one month before its official unveiling at the Mid America Trucking Show in March.

International employed key test applications such as Computational Fluid Dynamics, a computerized application used to optimize design in the early stages of the process, and 1/8 scale wind tunnel testing for basic shape development. Then the testing moved up to Ottawa where full-scale testing was completed with a trailer attached.

“A vehicle driven in the real world will face a cross wind (the average wind is 7mph from a southwesterly direction) and you can simulate that with this test,” said Matt Lafontaine, vehicle engineering manager.

That testing revealed an 18% drag reduction improvement with the ProStar compared to International’s previous best-in-class model. The company claims its testing also found the ProStar scored considerably better than any other competing model.

But company officials say the ProStar (Pro because it was “designed by professionals for professionals” and Star to tie in with the company’s heritage) is more than just a sleek machine. Driver satisfaction – building a truck “that will get you drivers” – was also a top priority in the design process, as was uptime and lowest cost of ownership.

“We focused not on the truck we wanted to build but on the kind of truck they wanted us to build,” acknowledged Baughman, referring to the dealer and customer advisory boards that drove much of the decision-making during the five-year, $300- million development of the ProStar.

More than 2,000 drivers were measured so that International’s engineers could figure out the best placement for instruments and controls. The company also conducted task analysis using video in cabs to see how drivers moved during their daily driving routines. And designers from International’s Fort Wayne Truck Development and Technology Center slept in a variety of tractor sleepers and went on the road with drivers throughout the development program to better understand driver requirements for living and space utilization.

Some of the features built into the ProStar as a result of all the research include integration of the seat, the cab and the chassis suspensions to complement and enhance vehicle level ride and handling, flexible positioning of the steering wheel and steering wheel-based controls, improved storage space options, enhanced HVAC system performance and a roomier feel to the cab with more natural light.

Getting the most out of the truck, of course, requires a reliable design.

“We spent a lot of time with customers mining their maintenance records and discussing the top causes of downtime,” said Baughman. “Every targeted system improvement has been tracked ongoing from component testing through to vehicle testing to be sure we provide a product that stands up to the gruelling and time-sensitive demands synonymous with line haul applications.”

Some of the top causes of downtime are tires, electrical harnesses, connectors, batteries, air leaks, air brakes and fuel systems. To respond to the issues, International developed monitoring, prognostic and diagnostic systems to improve uptime performance and provide information to the drivers and fleet managers. More than 25 production validation tractors made up the in-field testing component, and have accumulated more than 6 million miles of road testing since late 2004.

International also strove for lowest cost of ownership with the ProStar. For example, transmission replacement time has been reduced by 90 minutes, headlight lamps and windshield wiper blades can be replaced by a driver or mechanic without tools and a four-piece bumper design means only damaged pieces, rather than the whole bumper, need be replaced in the event of an accident. And innovations such as the E-Z Tilt hood and a Tilt-Away bumper provide a walk-in engine compartment and allow easy engine and underside access.

Service intervals have been synchronized so that customers gain an average 59 more days on the road over the life of the vehicle, according to International.