I've had similar experiences when using the ERS (Electronic Range Selector) to downshift in order to use engine breaking going downhill towards intersections. It definitely feels like the Jeep is speeding up when it shifts down, but maybe it's only an illusion cause by increased revs. Engine braking is not very useful with this transmission, in my opinion.
My '14 shows 2 L/100km (117.6 mpg) when coasting.
I agree with you, When I am in cruise control my TH will downshift and keep the speed about the same going up a hill, but with cruise on and going down hill it just speeds up until I have to brake some. Even in ERS I have to get it to the lowest ERS position to do anything and that is about too low.
2017 Trailhawk L Plus 4 bX4,Rhino exterior,Power 8 way drivers seat, Willys in windshidel,Cold Weather Group, Comfort/Convenience Group,Trailer Tow Group, 3.2 -Liter V6, Black Hood Decal , Uconnect 8.4 , Safety Tech Group, Leather Interior Group, Ventilated/Memory seat Group,Navigation. No hole in roof.
2017 KL Latitude-4 by 4 Cherry Red, V-6, Safety/Convenience group, Cold Weather Group,which includes heated front seats--love those heated seats,