The ES44C4 (Evolution Series, 4400 HP, AC traction, 4 traction motors) is the newest model in the series. It is similar to the ES44AC, except that it has four traction motors instead of six. The center axle of each truck is unpowered, giving an A1A-A1A wheel arrangement. BNSF Railway is the launch customer for this model, ordering an initial batch of 25 units numbered 6600-6624.[6] As of November 2011, BNSF is the only buyer of this model and has 300 units.
A unique feature of these units is that there is a variable traction control system in their computer systems. One of the differences between an ES44AC and an ES44C4 are the air cylinders and linkages on the truck sideframes of the ES44C4; these are part of the traction control system. Every time a variable in grade, traction, or wheel slip occurs, the computer will adjust the pressure in these cylinders to maintain sufficient adhesion, by varying the weight on the drive axles