[spotman]

This is a good thought exercise, but kind of comes across like a random equation looking for an explanation rather than interesting observation in search of an explanation.

I can't imagine the person driving doesn't spend as much or more than the person walking on food.

If we are saying that this small amount of money VS drinking oil is where the line is crossed, then are we not all comfortably well past this zone anyways?

So another way of saying this is listening to music is most efficient if you listen to a pre recorded song or you whisper only.