Using Festival Bus you can listen to any radio station outside of the vehicle.

Installation
1. Install ScriptHookV
2. Install the latest ScriptHookVDotNet
3. Download NativeUI version https://gtaforums.com/topic/809284-net-nativeui/
4. Download Guadmaz' Map Editor
https://www.gta5-hub.com/scripts/map-editor
5. Move DJConcert.xml file from the .zip into your GTA 5 main directory,
6. Load DJConcert.xml with Map editor.

Usage: While in-game get in the bus choose your radio station and choose leave the engine running option with simple trainer. Make sure that headlights are turned on
https://www.gta5-hub.com/scripts/simple-trainer-for-gtav
Then leave the bus.