2013 EB with 6speed here. I'm towing a 5er at about 8300lbs. Here in Ohio, it's relatively flat. But with the hills in Pa. and the mountains of W. Virginia and Virginia I have no problems with engine braking, which actually surprises me some. I leave the tow/haul on, turn the cruise off and decellerate to just under 60, and let it ride. Stab the brakes maybe 2-3 times and then I'm done. The rockies might be a slightly different scenerio, but I doubt that much. Still a working man so I'm sure when I'm able to get that far west, I'll have a bigger TV.