Sands80. You might just be getting the proper mileage for all the factors involved. Others may be quite happy to consult with you on that. I would take a more zen (?) response.
Perhaps consider instead, what's the $/mile? I filled up our '15 Golf last night. Fuel was at $2.359 (RUG was $2.139 at the time, I like to check so I can estimate in my head what MPG I'd need from a gasser for break even MPG -> 40MPG, can we afford a 40MPG gasser my wife would enjoy better for the same price or less . . . ? . . . ).
That $2.359 calculated out to $0.053/mile. For the record, 29,655 lifetime miles, 44.558 lifetime MPG. Yeah, that's approximately $159 we've left on the table by not getting 50MPG during the 23 months we've owned the car, $7/month . . . for you, that would be more like $80 gross if nothing changes by the time you approach 30,000 miles . . .
If it's worth it to you to worry about or pursue better MPG, more power to you, I don't mean to suggest there's anything bad about your concern. I just wonder if the perspective and expectations of some TDI buyers has gotten a little out of adjustment . . .