I just got the OGP yesterday and the first thing I tried was to connect it to my car. It works and yet it doesn't.
Even though the phone only does MTP, my car does read the internal SD of the phone. This would be OK if the internal SD's available space was truly 32GB, but because of how the phone is designed, the actual memory available was more like 22GB. If you install a bunch of apps, then that space will decrease even more. Simply put, all my music wouldn't fit anyways. I have about 1GB more than 22GB and I don't want to max out internal storage (I like apps!).
I didn't take the chance to see if this new phone has the same issue as my old phone, where the car only reads a VERY small portion (30 out of 1000+) of the music collection. I'm thinking that when this issue happened with my old phone, it could have been my car... I can't tell for sure and honestly could care less now.
I decided to just use my phone as an MP3 players for my headphones and I bought a separate memory card for my car. It's not what I'd prefer, which is a single device with all of my music on it, and could be played with both headphones and my car... but it works. So problem not solved, but worked around.
Overall, I am absolutely loving this phone though! Thanks for your help Lisa, and for your OGP review! (I watched it like 100x and compared it to your reviews of the other current smartphones!)