There has been discussion elsewhere about whether the 2017MY car has CarPlay. The local iGenius seems unaware of how it works, so I hope this helps - for a 2014 car.
I have an iPhone 6s, and found that it shows no available cars in the list when I select Settings/General/CarPlay. 
It also suggests that I should press the voice key on the steering wheel to access CarPlay. But that doesn't work: the car simply asks me what I want to do.
However, if I access Settings/General/CarPlay on the iPhone, and then press the MODE button to the left of the car's volume knob, silence. (MODE seems to switch between the available audio inputs - Radio or Bluetooth - so Bluetooth must be on.)
Then, if I start to play something on the phone, it comes out of the car's speakers!
When I get out of the car and lock it, sometimes the playing is paused and sometimes it reverts to playing on the phone's speakers. If it pauses playing, it resumes when I get into the car again where it left off. If it didn't pause, a message comes up on the lock screen letting me pause it by hand.
