When people are driving, they don't have the time to create new playlists on the go. And many times listen to the same songs over and over.
What if people using these new systems in cars could "tune in" and listen to radios created by people.
These would not be playlists, but internet radios, where the person in charge could even speak.
This, like any radio could play ads, the ones that already play in spotify, and could in fact lead to some revenue to the person who manages the radio.
A similar idea has also been suggested here:
Add your kudos and comments there please! ;)