> what can I do to ensure that the cars surrounding me (windows up, listening to music, carrying out conversation, probably fiddling with a phone) are aware of

> what can I do to ensure that the cars surrounding me (windows up, listening to music, carrying out conversation, probably fiddling with a phone) are aware of my existence without making noise? Your implicit assumption is that if you make enough noise, you will pop their "windows up, listening to music, fiddling with a phone" filter bubble. And that noise is the most efficient way to do this. I wonder how much noise that would take, esp in more modern cars with good soundproofing? Or perhaps other methods might be more effective?