Audi A3 7 inch Built-in CarAutoPlay and Android Auto and DSP Carstereo Carplay dab

Highly Recommended!!! CarPlay is a smarter, safer way to use your iPhone while you drive. You can get directions, make calls, send and receive messages, and enjoy your favorite music. All on your car’s built-in display. And CarPlay now features more app categories and custom wallpapers for your CarPlay Dashboard, and more 

Android Auto is a system that integrates your phone into your car's entertainment system. It can mirror the phone's screen on the car's display screen, allowing drivers to control their phone using voice commands or the car's touchscreen to minimize fumbling with a phone while driving.

​​​​​​​​Learn more at the link below

https://www.apple.com/ios/carplay/

DAB is Digital Audio Broadcasting. Not available in the US. List of the countries below 

https://www.worlddab.org/countries

Onboard Diagnostics II (OBD2) is a diagnostic system. It is used to check the engine and other vehicle systems and communicates with all the possible glitches that happen to them. OBD2 is a vehicle diagnostic tool that can be connected to the OBD port of the car under the steering wheel. It shows fault codes via an app at the head unit’s screen. 

https://www.sigmacarstereo.com/obd-ii-diagnosis-adapter

 How to connect OBD2 dongle
1. Connect the OBD2 adapter to the OBD port under the steering wheel.
2. Turn on the Wi-Fi of the stereo and connect it to the "OBD" WiFi signal.
3. Open the "Torque" app to use.Note that Wi-Fi OBD and wireless carplay do not work at the same time because the radio only connects to one device through Wi-Fi.