How do you play the radio in Audi a3 with the engine off?

To play the radio in an Audi A3 with the engine off, simply press the power button on the infotainment system or the volume knob to turn it on. The radio will operate in accessory mode, allowing you to listen to music without starting the engine. Keep in mind that using the radio for an extended period while the engine is off may drain the vehicle's battery.