You may not be the only one who find that when you plug your iPhone into your cars stereo or connect via bluetooth that the first song in your music starts playing. This is super annoying especially if you have a really crappy song. For me it is Kayne West Addiction. I know I should just delete the song, but for some reason I like to keep full CDs.
For some reason even if you have shuffle enabled, Apple decided that it will start playing the very first song in your music library before it will shuffle the other songs. A really cool trick to stop this from happening is to create a .mp3 file that is about 2 seconds of silence and then name it so that it appears first in your song libaray. Choose a song name like Aaaaaaa and an artist like Aaaaa. That way it will play your new .mp3 file first and then hopefully shuffle to another song.
You can download a blank or silent mp3 song from here: http://www.xamuel.com/blank-mp3-files/2sec.mp3. Next just open it in iTunes and change the artist name and song name. Then sync it to your iPhone or iPod Touch
Hope this fixes your issue and is no longer annoying like it was for me.