My wife has a 2012 Impreza hatch and the bogus mpg ratings do not justify the low power. She averages 26.5 mpg in a 50\50 split city and highway and rides on the highway at a consistent 65-70 (My 02 RS got better MPGs with more power.). Keep in mind we live in CT so we only have large hills forget living anywhere with actual mountains.
Her previous car was an 09 Forester so the Imp was an improvement in the MPGs but no where near what is claimed, I'd assume this will also be the case with the XV.
As far as the XV's appearance it looks like an Impreza, the slight change around the fog lights, black moldings and a few more vertical slats on the lower grill do not make a new model. If I blind folded you and put you in the front seat you couldn't tell the difference between the two.
Personally I think they should have done more to separate the two from each other. Do I think the XV will sell as is? Yes, but it think it would have sold better if there were more changes.