Q&A

I would check your road speed sensor data or mph sensor, by using a data streaming scanner, or have a shop do it. Then you can compare the road speed sensor data with the speedometer, to see if there is a difference. Does the car shift normally? Is there a Check Engine Light on. I ask this because this may help you solve this issue. If the road speed sensor was defective, there may be a Check Engine Light, for a speed sensor code.

do you have the right size tires on the car? tire diameter will affect this greatly. it is also acceptable for a speedo to read higher than the car is actually going by up to about 10%. some questions are does it read "0" when stopped? does the odometer measure miles correctly?

I have the same problem and I have confirmed it against a GPS and road milieage. My 2006 records a faster speed than it is actuially doing (105 km/hr when it is only doing 100)I brought this up with my VW dealer. They informed me that a this was within tollerance.
This error allows VW to end my warrantte at 5% kms sooner, so when I reached by 80 000 km and ended my warrantee, I had really only put 76 000 kms on my car - Pissed.
In addition, when one calculates the mileage per gallon, one gets a reading of 5% higher than it really is.