Navistar International held a press conference call last week to announce the official launch of the International ProStar ES, its most fuel-efficient Class 8 highway tractor ever. ES stands for “efficiency specification.”

Fuel-efficiency gains come in the form of a better-integrated powertrain, aerodynamic tweaks and enhanced support from Navistar’s Performance Engineering Team and its OnCommand Connection telematics platform. The ES could net a fuel economy gain of up to 11% compared to an EPA10 ProStar baseline with a 13L MaxxForce engine and manual transmission.

Powertrain offerings will include a 13L International engine with the 10-speed Eaton Fuller Advantage Series automated manual transmission, or the Cummins-Eaton SmartAdvantage, featuring an ISX engine with that same Eaton transmission.

The powertrain alone will contribute a 3-6% fuel economy improvement over the same engine mated to a previous-generation UltraShift Plus, International claims.

The exterior of this ProStar looks no different than previous versions, however the company is touting what it claims to be superior aerodynamic performance in all wind conditions, including crosswinds. The ProStar was designed with the concept of “wind averaged drag coefficient” in mind, so that it performs equally well when buffeted by crosswinds as it does when slicing through the wind head-on.

The Performance Engineering Team is available to work with fleets to spec’ the truck appropriately for their specific drive cycles. Basically, the idea with the ProStar ES is to provide customers with the most fuel-efficient spec’ right out of the box, with little or no modification required. The truck goes on sale next week. You can read more about the new offering here.