I tried it with a range of km to see how the mileage affects the result.
2013 Golf Comfortline 6sp
50K km $17,050
65K km $16,200
70K km $16,200
72.5K km $15,050
75K km $15,050
85K km $15,050
95K km $15,050
100K km $13,600
105K km $13,600
I am currently at 74,500 km so my current number is $15,050 which is quite a bit lower than I was expecting
It is evident that the mileage steps are large (large km range) and large $ difference when you change range. That may cause some surprises when people get their offers based on updated mileage.
The way I understand this, the mileage ranges should shift up over time (meaning same dollars for higher mileage) as we go through the buy-back period. Ie waiting until the end of 2018 may give you a better result if you are near the bottom of a range and your mileage hasn't changed much (or a worse result if you are near the top of a range and put on more than the average kms).