Radio. I expect "soon-ish" to not be able to anymore, since they're going to change to a "new" way of broadcasting (my car - and thus the radio - is fairly old).
I like music in my vehicle, but I've been into phases where I like silence or talk radio. Anyway, I used to visit my wife, while courting her, and the trip was 2 hours each way, so music in the vehicle was important and they had this really great oldies station I liked for a long time, and it only came on once I was within an hour near or away from my destination.
I use Spotify on my phone 99.9% of the time when I'm listening to stuff in the car. The .1% that I don't is when my phone doesn't want to connect to the car's Bluetooth (which is pretty rare) or when my mom and I are in the car together and neither of us turns the radio on (or I don't turn my Spotify on).
I don't drive at the moment but whenever I am in a car with say my mum, brother or grandma they either have the radio playing or they have they connect Spotify to their in-car Bluetooth.