Cell phones forum: Options for playing MP3's on Droid in car?

I'd go bluetooth if your car supports it. But the Droid headset jack has support for 3.5mm stereo headset and voice. Although with the patch cord in, you might want to put the Droid into airplane mode so that you don't get calls blasted all over the highway.

It's the least desirable method, especially inside a car that has enough issues already dealing with road noise ;(.

If you get a car stereo which has USB jacks on it, these units essentially just have a mass-storage reader device which effectively takes a USB memory stick and mounts it into it's operating system as a readable file system. Well, when you plug in the Droid into the stereo, the phone should then prompt you in the notification bar asking if you want to mount the USB storage, and so you say yes, and it should go ahead and allow the operating system of the stereo mount the Droid's built-in 16GB SD card as a 'removable storage' device. I have a Droid and this is how it works when you plug it into a computer. You plug it in, and Windows doesn't see it yet, but Droid does detect that Windows is querying it and wants to mount it to the file system. Then Droid asks me if I wanted to mount the USB, I say 'yes' and then it says 'mounted' and then if you go look in Windows it shows up in Windows Explorer as 'Removable Storage' and then I can read an write to the 16GB SD Card which is under the battery. The Droid already comes with a USB data cable which doubles as a charging cable. While I haven't actually tested whether the car stereos with a front USB plug on them can mount the Droid's USB, all logic tells me it will work, because when you click yes in the Droid to allow mounting, it then should 'present' itself to the stereo as a valid Removable Storage device, which is part of the licensed Universal Storage Bus (USB) series of protocols. But if you would like to be sure about this before committing 100%, Droid / Verizon has a 30-day trial and you can take one over to a car stereo shop and test the USB connectivity on a deck in there and if it mounts fine and can read the songs you place on the SD card, then it should be fine. Usually the USB stereos can recurse into directories so it does really matter what folder structure on the Droid's SD card that you put your songs, it will automatically find any songs with the .mp3 .wav .wma and any other file extensions that the stereo supports. Hope this helps.