The IMpreza is a far cry from an SUV or whatever in terms of fuel consumption, but still much higher than a Corolla or Civic. But, for an AWD wagon, with 170hp, it's pretty good.
From the US EPA (and using US gallons):
Impreza 2.5i (either transmission): 20 mpg city, 27 mpg highway, 22 mpg combined.
Toyota RAV4 i4 AWD: 20 mpg city, 25 mpg highway, 22 mpg combined.
Honda CRV AWD: 20 mpg city, 26 mpg highway, 22 mpg combined.
Nissan Rogue AWD: 21 mpg city, 26 mpg highway, 23 mpg combined.
Jeep Patriot 5MT AWD: 22 mpg city, 27 mpg highway, 24 mpg combined.
Not very impressive in my book.