The advanced key is an electronic access and authorisation system.
To unlock and start the vehicle, you only have to have the key with you – there's no need to look for it and take it out of your pocket.
As soon as the driver carrying the key stops within approx. 1.5 metres of the vehicle and moves his/her hand towards the door handle, the key is identified by means of a proximity sensor in the vehicle door and a radio pulse generator in the key housing.
The vehicle is automatically unlocked when the door handle is pulled. For unlocking and starting the vehicle, the advanced key can stay in the driver’s pocket.
If you only wish to open one specific door – without releasing the entire locking system – you can set the advanced key function accordingly via the MMI, if installed. Incidentally, the luggage compartment is unlocked independently.
Article source: www.audi.co.uk