Slightly offtopic, but related to VAG TDI mpg.
As you might've seen in another thread, we've taken delivery of a new Audi A1 1.6TDI Sport. The missus is taking her driving test (at 38 years old) in a month's time after a 12 year break from trying.
So i've decided to give the 7R a rest and run in her new A1. I've done about 90 miles in it over 3 trips, getting a consistent 56mpg. I second guess the car's gear change suggestions - we seem to be on the same wavelength.
Took the missus out on the L plates today, she was driving up the north Sea coast from Tynemouth to Blyth and back.
The missus was almost always 1 gear lower than I would've been in (sitting at 20mph in 2nd, 30mph in 3rd, not hitting 4th unless doing 45mph), and on that 18 mile round trip I was astounded to see the car had given 65mpg indicated. Driving the car in a way that would seem to be uneconomical has given the best result.

Diehammer- unless you want your injection system cleaning, I would avoid Shell V-power diesel - it is less calorific than regular diesel, so will give you fewer mpg.
My GTD ran best on BP and Esso. A string of pre EU6 TDIs owned always had a preference for Shell, not the 7GTD in my experience.