I rip my music CDs to MP3 (at least 320 Kb/s), then burn them to CD-R. This allows me to get at least 7 music CDs on a CD-R. But I'm starting to think that the next time I'm in need of a new car stereo (mine works fine with my MP3 CDs), I've seen that some of the newer ones actually have USB ports on them, I've been thinking that it might be nice to have one of those, especially given the fact that 4GB thumb drives are so cheap now, less than $25.
Mark
The iPod connects to the car player, and on some cars the steering wheel controls auto-sync to it.
You might want to try something else if your equipment can support it. A 256 Kb/s AAC would probably sound the same as that 320 MP3, and take a lot less space.