My trip computer is reading over and I want to adjust it with VCDS. Question is, does the new figure need to be a correction on the output figure i.e I tell it 94% or does it need to be told that it's input figure is an over-read i.e 106%?

To lower an over reading display you need to increase the %, I have done a couple of Superb’s and on both of them 1MPG = 2%

They were both over reading by around 5MPG, so I increased it to 110% and it is as near as spot on now.

Cheers Gizmo.