You just choose a superlong playlist before starting the car and then play it randomly. You don't have to interact with the phone.

Last time I had a car I had an old mp3 portable mp3 player constantly hooked up to the car with 4GB of music inside. I would just hit play and drive and would only adjust volume from the steering wheel if I needed to. If I had a car again I would probably do the same, that is the lowest distracting way to have music in your car.