I've taken an SD card with music on it and plugged it into my E450 and have been listening to that. As I think there are other sources as well, and as I'm thinking of reorganizing my music cards/USB-sticks, I have some questions I was hoping someone here might be able to answer:

I believe that other than the SD card port in the glove compartment, there are other USB ports in which music can be placed. What other USB Media Sources are available, and where are they located? I know one USB port in the front is dedicated to Android Auto or Apple Carplay. Can it be used for music as well? What other ports can be? (My wagon has no USB ports in the console in front of the rear seats, but I imagine those would be only for power anyhow.)

How are each of the cards identified? Simply as SD, USB1, USB2, or can the system read the card's Title and display that? Like "Oldies", "Contemporary".

The other question concerns the media card's folder and filename format: Does COMAND get the Artist and Album name from the file structure (like on my GTI - \Adele\25\01 Hello.mp3), or does it get the Artist and Album name from each file itself, meaning all files could be in a single folder (or so), but Artist & Album would still be correctly displayed from each track? Also, is album art downloaded by COMAND, or must it be on the media card?

Any other information or suggestions you feel would be helpful to me here would be appreciated.

USB ports are not dedicated to anything. Just like a USB port on your computer, they can work with many different devices. My E300 has 3 USB ports and 1 memory card slot.

Each media port is named/numbered which you can see on the media source menu. Why don't you put a few albums/music files on a memory card to see how the system works. Also there are several threads on the forum that discuss this subject.

The one in the front behind the front passenger cup holder is dedicated for Android Auto & Apple CarPlay, however can be used for usb drives. If you use any of the two in the armrest neither Android Auto & Apple CarPlay will work.

Really? Well, that really sucks. The only reason I don't use Android Auto on an every day basis, is that I tend to forget my phone when leaving the car, but on trips I intend to use it for navigation, etc. But then my USB drives won't work?? I'll have to try that.

Get a holder for your phone, see attached. I was forgetting my phone too

I just did a test, using an SD-Card and two USB drives, all connected in the center console. Of course, I can switch, using Media, to any of those drives, and I can also switch using Media to my Samsung phone (connected with Bluetooth, not Android Auto). I then connected the phone with the cable and started Android Auto. Of course, Bluetooth is disabled for the phone then, but I can play Pandora using Android Auto, and I can also play, selecting Media, any of my SD or USB drives. So they do seem to work fine with Android Auto, which is good.

Correct! Any device can work in any USB port. AA and CP applications must use the USB port in the forward console.

A real pity MB did not program it so that when you stop the engine, a warning about your phone in the armrest is still there. The Bentley GT has also CarPlay and offers this warning (and probably this also is true for other VAG cars like Audi, etc?)

Yeah, but to be fair, my wife's new Kia Niro has the warning about the phone, but I still seem to ignore it. ;-)

I should think that "there's an app for that" to tell you when power is interrupted when you turn the engine off? Has anyone looked?

You mean an app on the phone to do this? Could indeed be, but since it is hidden away, an alert on the COMAND screenwould be more useful (as it is in VAG cars, and apparantly als in the Kia )

The power to USB ports and 12v receptacles does not shut off when the engine is shut down. There is a delay of several minutes before the power shuts off.