I've been driving a new 2016 4x4 Summit with 5.7L V-8 for two months. I commute ~550 miles/week, mostly on freeways. Once I get on freeways, I push the button on the center-stack that activates Eco-Mode, and I have been very impressed with its performance, torque power and fuel savings. (I shut off Eco when traveling 2-lane roads. I use it only on highways.)
At any rate, I recently got to wondering if the Eco system always shuts down the same four cylinders; or, does it randomly vary the four cylinders which are shut down in order to mitigate the potential for uneven cylinder wear?