I want to give an indication to SD cards here.
When I use Micro SDHC cards (SD adapter) are not displayed via the RDS MP3 ID tags. Under normal SD cards it works, however, without problems. Perhaps newer devices have a modified software and the problem I resolved to date.
So if you have trouble viewing the mp3 tags on the car radio and uses SDHC cards, it should be with a normal SD cards try again.