Ok so its not a Furby but a poverty Golf TDI (110 i think as its only got a red i)

Mate says that he can hear a ticking while driving and it gets louder the quicker he goes. There is nothing at idle or at load when stood still.

Short of having an extended break and driving it ive not got an idea. Anyone give me a clue to help a mate out?

It's his watch.

Nail, screw stone etc in a tyre is a possibility