I heard back from Lexus and I don't think they understand the mp3 dvd issue, here is the reply I got:
"Thank you for contacting Lexus GB.
I can confirm to you that the MP3 files stored on a DVD disc will be able to play in the Mark Levinson audio system. However you will need to make sure that the DVD disc that the MP3 files will be stored on, has the official DVD Audio mark.
The following DVD disc formats may not be playable in the DVD system:
DVD-R, DVD+R, DVD-RW, DVD+RW, DVD-ROM, DVD-RAM. Please refer to the category DVD compatibility in the Lexus vehicle owners manual.
If I can be of any further assistance, then please do not hesitate to contact me.
Kind Regards,
Sean Lester
Lexus Customer Account Manager
Phone: 0845 278 8888
Email: lexusinfo@lexuscontactcentre.co.uk
Webster: www.lexus.co.uk"