3.5 Eco Beast here and averaged 13.6 liters per 100 for all of last winter including command start times etc. etc.
Just got back from ski doo trip hauling cargo trailer, sled, gas, gear etc. and did 17.5. Boys at work are in the 19 plus range with their Hemi's in the winter, empty, so think I'll stick with the eco as I do quite a bit of towing. And towing it does, works like a small diesel, only drawback, it sounds like a sewing machine !!! Looking at trading later on and will again go with the ecoboost as new ones have more torque plus the 10 speed tranny. Service manager at the dealer was telling me that lately they have had to rebuild some 5.0's and no ecoboost, so they must be better than they were when they came out cause they weren't that good at first ??