You need to know what music file format the Lexus takes, I assume it's MP3 as it's the most common
Unfortuntely not all devices take AAC which is the format of music sold on iTunes and perhaps ripped from CD's with as a default setting in iTunes.
You need to convert the AAC format of your music to MP3 with third party software, Apple only converts MP3 to AAC in iTunes. 😟
You can try the tips in this post. Hope it helps.
http://forums.macrumors.com/showthread.php?t=275717
If you initialize the USB in Disk Utility, it has to be a MBR partition map FAT32 (MSDOS) format.
But if you uinitilized it on another device automatically it will do that for you.