I have a 2020 GLC SUV that didn't come with Sirius, so I've been having to use the Sirius App on my iPhone and CarPlay. My main complaint is having to plug and unplug the phone all the time. So I decided to use an old iPhone 5 that I have, without a SIM card, and sign up my GLC to the ATT data plan for the GLC, that way I can get internet data into the car and use its Hotspot and WiFI features. Also I can leave the phone in the car plugged in all the time. Its only $10/mo so its also cheap. So I setup the GLC with WIFI active on the ATT network, plus I also created a Hotspot. Now the iPhone 5 recognizes the GLC's WIFI and connects to it. I don't let it join any other WIFI connections. Bluetooth is also turned off. So now when I plug in the iPhone to the USB C connection, most of the time CarPlay starts up, then I can choose the service. Most of the time Sirius XM will start when I select it. However, it doesn't do it all the time, ie. sometimes it says it can't connect to CarPlay and sometimes Sirius won't start. So its frustrating. Also, some nights when I turn off the car with the iPhone still connected to CarPlay and Sirius was active, the iPhone will be totally discharged in the morning. Also, when I shut off the engine and leave the car, it appears that CarPlay and Sirius are still running. I don't hear anything but the screen on the iPhone shows Sirius as active. Is that because the GLC's power remains on for some period of time even after I turn off the car and go off? I'm trying to figure out how the CarPlay system is working. Does the iPhone use the GLC's WIFI connection to get internet connectivity so that when Sirius starts up it can then connect to Sirius and receive music, which it then sends to the GLC's headunit through the cable connection over CarPlay, or is something else happening? Sometimes, when this is all connected and running, I don't hear songs, and the iPhone is sending the music to the iPhone vs. CarPlay. A real mess and frustrating. Do I even need to have the WIFI active, or does the USB C cable connection between the iPhone and the MBUX connection for CarPlay make the internet data connection for Sirius active so the Sirius App can receive music data that then gets passed through CarPlay? Is there a way to turn off Sirius after a certain period of time? I don't think the auto-lock feature does this, but I may be wrong. I know I've posed a lot of questions, and I hope that some of you may have some answers and solutions. Thanks.

Well I did a test today to see if WIFI is needed for Sirius, and it is. I got things started with CarPlay and the iPhone WIFI on and connected to the GLC's new WIFI connection, and it connected to Sirius and played. Then after 10-15 minutes I turned off the WIFI on the iPhone. But Sirius continued to play! Why? Well after about 5 minutes of no WIFI, I got "Trying to Connect" message in CarPlay, and then after a minute or so "NO CONNECTION". So I turned WIFI back on, and in about a minute it connected up and started playing again. Finally I realized what I think is going on. The Sirius App on the iPhone is storing music data in a cache file on the iPhone, and when I turn off the WIFI on the iPhone, no data is coming into the phone, and the data in the cache file is slowly being consumed. After 5 minutes, the cache file is empty of data, and "Trying to Connect" comes up, and then NO CONNECTION. So I think that's what's going on, and thus my conclusion is that WIFI needs to be on and connected to the GLC's WIFI connection in order to connect and download from Sirius, and probably any other App that's in CarPlay. So, I still have the other questions/issues to resolve.