Samsung G3 interface with Prius C 3 question...

This is a hard question.

First of all, when you say you have a "Samsung G3" phone. Do you actually mean you have a Samsung Galaxy S III (aka. SGS3, GS3, SGSIII)??

Now for the bad news. I do not have the built in nav screen in my C, so I can't plug in my android phone and figure out what you're seeing. I also am running a very different version of Android that your phone is running, so I can't speculate on what changes Samsung made to the data interface of your phone.

With that being said. Typically an android phone (with android 4.0 or higher), when plugged into another device via USB, will connect using MTP (Media Transfer Protocal). The way MTP basically works, is it provides a tree of files that are located on your phone. The stereo can then traverse those files and pick and choose the files types that it knows how to play, and then list them with categories on your display. The head unit itself could be doing any kind of renaming, and organizing it sees fit. For instance it might go through the files on your phone, pick out all the music files and look at their artist in the metadata, and then list them all by artist. If it does that, you will probably see duplicate artists showing up in the list. Some have a capitol letter, others don't, maybe a missing symbol, or an extra space in the name. If the artist text doesn't match up perfectly, it will be listed as a different artist. It is also not uncommon for many music files to not have the correct metadata. So then if the unit displays your music by artist, it could be shoving a bunch of music into an artist with a blank name, listed as 'Unknown' possibly, which would explain your missing music. As for the podcasts, I don't know how those work, I've never been into them. You podcast app could be saving all sorts of weird data on your phones storage card (internal storage, or internal removable mSD card).

The best way for you to figure out what is going on is to first see if your radio unit has settings for usb playback, and if so, change it to show folder structer, not by artist or file type. This should let you see which folders on your starage card are getting read by the unit and have stuff in them. Then you can plug your phone into your windows computer, and brows the files. Try to find where you have your music stored, and where those podcasts are stored, and see if there is actually duplicates.

Good luck!