Either mileage is improving, or I'm learning how to drive the car smoother.
The GTI gets commendable mileage when going at a steady speed, but any acceleration or turbo usage really cuts into it. Drove to a wedding this week-end and with the cruise set at 122km/h (and with the A/C on for about 1/3 of the trip) I managed 685kms/tank. Not so bad (the display showed an average of 7.2L/100kms on the way down but reset itself for the drive back). I'm sure I could have bumped it over 700 easily by driving a few km/h slower, had I not encountered heavy traffic in Oakville, and not had the A/C on.