I've got a A3 3.2 S-Line with a DSG gearbox bought new in November. The last 4-5 weeks there is a knocking/tapping sound coming from the underside of the car. It only knocks when the car is travelling and it increases in frequency along with the car's speed. Took it back to the dealer and they said it was stones in the tyres!! It is defiantly a mechanical noise.
The noise is getting slightly louder ( even after the removal of the tiny pebble ). Could it be a problem with the engine or transmission ? I hope you guys can help, as the dealer thinks I'm hearing things.

 

sounds like a deformed tyre to me the car is too new for a bearing to go, change the tyres round see if the noise is transferred to the rear I have had a few new cars with this problem cheap tyres getting through the system