How do I access the hidden features in the Audi A4 infotainment system?

I have heard that there are some hidden features in the infotainment system of the Audi A4. Can anyone tell me how to access them and what they are?

To access the hidden features in the Audi A4 infotainment system, first navigate to the settings menu. Then, hold down the 'back' button for ten seconds until a new menu pops up. Here, you can find additional features such as a hidden test mode and advanced diagnostics.

To access the hidden features in the Audi A4 infotainment system, simply long press the menu button on the main screen. This will bring up a hidden menu where you can adjust settings and access extra features such as a performance tuner.

I have found a shortcut to access the hidden features in the Audi A4 infotainment system. Simply hold down the info and navigation buttons at the same time for five seconds. This will bring up a menu with additional features and options.