Using Festival Bus you can listen to any radio station outside of the vehicle.
1. Install ScriptHookV
2. Install the latest ScriptHookVDotNet
3. Download NativeUI
4. Download Menyoo PC SP
5. Move music.xml file from the .zip into your GTA 5 main directory,
6. Load music.xml with Map editor.
Usage: While in-game get in the bus choose your radio station and choose leave the engine running option with a simple trainer. Make sure that headlights are turned on
Simple Trainer for GTA V
Then leave the bus.