I took a USB 2.0 8GB Kingston thumb drive and decided to test to see if I could load music in my car. I downloaded some songs to my mac (I usually just have them on my phone). The HD If Available checkbox was checked in iTunes and I copied the directory structure that iTunes uses directly onto the drive. The files are m4a files. Anyway when I put the drive into the car the USB option shows up and when I select it the car can see the files. When I select a file it shows artist/album/artwork etc... but I get a loading error on all the files. Any thoughts to what I need to do to support this? I can use my phone no biggie but I thought it would be kind of cool to have all my iTunes music in my car. I wanted to test on an existing USB drive before I purchased a larger one that would be dedicated to the car.