iPod & car player

[amilesi]

Hi, I am trying to lissen music connecting my iPod to the USB port of my car player. Since once connected the iPod is 'freezed' and therefore I cannot navigate through songs (or at least I find it difficult to go through the various F01 F02 ...) I have enable the iPod as a disk. Than I have created separate directories with music files inside. The car audio recognizes the directories (almost) but does not reproduce files in the correct order. My files are 01.mp3 02.mp3, .....
Is it a problem of the car audio player or it something related to the iPod files ordering?
Thanks
Andrea