Hi Johncore, the sport button selects different settings for the auto box. if you are already using kickdown then you won't notice a difference. essentially what the button does is tell the ecu to use a "sport" setting, for example, switch it on and you should notice the box staying in a gear for longer than if you left the button off. it also changes the program to enable the box to change down quicker (both a quicker gear selection and a more responsive accelerator, just proding the accelerator will change the box down instead of have to press all the way down)for easier overtaking.
The later A6, etc, came out with the DSP which uses the ecu to learn your current driving style and then selects between 5 programs automatically.
Your box just has the two, sport or normal/economy....
hope that helps.