What app do I need or what format do I have to save the music to be able to use it on my car stereo using the USB port
You don't need an app.
Use the car stereo to access the music files on your Droid X.
Your car stereo has to be able to detect the phone as a USB Storage device. If your car stereo isn't able to detect it as such, you will not be able to play music from it.
If your car has a 3.5mm AUX in jack, purchase a "3.5mm male to male" cable and play through your headphone jack of your X.
The Point is, if your Car Stereo has a USB jack then it will probably be able to see all the music on your DX and play it. At least the MP3 files but perhpas WMA files as well as Itunes off an IPOD or Iphone.
yeah should be able to just plug it in chose the input device on the radio options and use the phone as normal for music ...i like the headphone jack method also but a little nifty secret if you have a model with both a usb and headphone jack plug in both and play via the headphone jack and the usb will charge the phone ....this works on my kenwood reciever takes a little longer to charge but not as restricting as the short car charger cable .......why do they kink these and make them short why not a longer straight cord like with home chargers?
