Hi
I also have a 2017 A4 with the 1.4 TSI engine, albeit a saloon rather than the estate. Until last March I was averaging about 2000 miles each month, with most journeys being a minimum of a 20 mile round trip. Based on the onboard computer (which I once calculated to be about 7% optimistic), I usually get at least 50.4 MPG and often get nearer to 55 MPG. I use dynamic mode as I prefer the throttle response, but I tend to drive in a fairly relaxed manner. Mine is the Sport model with 17" wheels, so if yours is an S-Line with 18" or more wheels, that would probably use more fuel. Is yours a manual gearbox or DSG?
Hope that helps
Glen