LOUISVILLE, Ky., March 26, 2015 /PRNewswire/ -- At the Mid-America Trucking Show this week, International^® Truck announced new enhancements to its industry-leading fuel efficiency package —the International^® ProStar^® ES. First introduced in December 2014, the ProStar ES, short for efficiency specification, features industry-leading aerodynamics, the most fuel-efficient powertrain/transmission combinations available in the industry and a number of other advanced technologies. Together, these features enable the ProStar ES to achieve a total fuel economy improvement of 13 percent*—and more than 2 percent improvement since its launch late last year.

"The ProStar ES continues to leverage the latest advancements in powertrain and vehicle technologies to drive incremental gains and provide customers with the industry's best fuel efficiency package," said Bill Kozek, president Truck and Parts, Navistar. "As part of our 'continuous improvement' mindset, we're not standing still and we'll continue to enhance this spec with increasingly more efficient components and advanced technologies."

The ProStar ES is available both with the Cummins ISX15 and with Navistar's proprietary 13-liter engine (N13). The ProStar ES offers the Eaton-Cummins SmartAdvantage™ powertrain which pairs the Cummins ISX15 with the Eaton Fuller Advantage™ automated manual transmission. Enhancements to the ProStar ES with ISX15 include the integration of Cummins' ADEPT for the ISX15, which includes SmartTorque2 and SmartCoast. ADEPT is a suite of advanced electronic features for the ISX15 engine that interact with automated manual transmissions, adapting to operating conditions to reduce the variance between newer drivers and experienced experts. The system continuously makes minor adjustments to speed, power and transmission gear while monitoring current grade and vehicle mass to take advantage of vehicle momentum, maximizing efficiency and using less fuel in the process.

Cummins' SmartCoast enables the engine and transmission to work together more effectively to improve efficiency while coasting. On moderate downhill grades, the driveline is disengaged, allowing the engine to return to idle and reducing drag from the powertrain on the vehicle, conserving momentum and improving fuel economy. Cummins' ADEPT and SmartCoast are also available on non-ES ProStar models powered by the Cummins ISX15.

The ProStar ES with Navistar's proprietary 13-liter engine (N13) is available coupled with the Eaton Fuller Advantage™ automated manual transmission. The ProStar ES with N13 now includes enhanced engine controls, including a "neutral coast" feature that shifts the transmission to neutral when a driver backs off the accelerator, maximizing coast time and improving fuel economy.

The newly launched 13-liter engine is one of the lightest, quietest 13-liter engines on the market. With a downsped transmission option, the engine cruising speed drops below 1,100 RPM at 60 miles per hour, a significant reduction compared to traditional engines that operate at 1,250-1,300 RPM at 60 miles per hour. In addition, the engine's steep torque curve, strong structural integrity and low NVH (noise, vibration, harshness) provide for one of the lowest shift points in the industry at 950 RPM.

The ProStar ES, and other ProStar models powered by the ISX15 or the N13 are also available with XFE 75W-90, which is a new and innovative  fuel efficient axle lubricant that reduces friction and spin losses, improves durability and drives further fuel efficiency improvements.

"The ProStar has established a strong reputation among drivers and fleet operators as one of the most fuel-efficient trucks in the industry," Kozek added. "With ongoing improvements to the ProStar ES package, we'll continue our drive to offer best-in-class fuel efficiency for our customers."

*Compared to the 2011 model year ProStar/13-liter/10-speed manual baseline