BTW: Don't calculate based on the analog gauges, if in doubt use the digital display as reference.
Both the analog and digital speedometers read incorrectly. If I use anything for a reference, it would be my GPS of which I have three. Another thing I can do to confirm is to drive 10 kilometers using highway distance markers at a GPS speed of 100 KPH and it should take exactly 6 minutes. And if there is any doubt as to the accuracy of those distance markers, I can use another set further down the highway or better yet, take the time over a greater distance.
Also note that there are models which use secondary distance impulse number to calculate the distance travelled, so that may be off as well (meaning there may not be just 2 speeds you're looking at but 3)!
I know my odometer is off as well and reads high, provided of course those distance markers are accurate.
I think the problem is that VW's cafeteria serves too much Augustiner Edelstoff to their employees.