As I have at home - computer controlled watering system and car "entertainment" system. The later is not about the car entertaining me, but me entertaining the car by trying to coerce it to do what I want.
If I want to say play a Pandora station through the car's system I select Apps then Pandora. That seems simple. Then for the 10,000 time I have to confirm that I know that the phone company might charge me for data. Then I'll get a connecting message.
Typically this is where fun can begin. The fun is a failure to connect with a very unhelpful error message that might as well say "you lose, sucker". Given that this involves Pandora, the cell company, my phone and the car software, knowing what's wrong is left as an exercise for the masochistic.
I've learned through bitter experience that sometimes the phone forgets the Pandora login, sometimes the phone needs to be rebooted and even sometimes I've turned off something essential on the phone such as bluetooth in a desperate attempt to have enough battery left in case of emergency.
Actually having a helpful message would, of course, spoil all the fun.