Speedometer not reading correctly
 

Hi Guys,

Sorry that this is my first post, I will introduce myself in due course.

I am in the market for a b7 a4 and have found the perfect one (a lovely 170tdi sline quattro) however on the test drive it soon became apparent the speedometer is well off. We managed to take it on the motorway and when really giving it some and flying past everything on the motorway the speedometer was only indicating 80mph when it was definitely around the 100 mark. I would still like to buy this car and the dealer has said he will get it booked in to have it sorted. But I was just wondering if anyone has experienced it and what the cause was/could be.

Thanks in advance.

does the car have the correct size tires?