Honda is the low end. Acura is the high end. You wanna know the solution? CarPC! j/k.
It sucks that your car doesn't have support for MP3 or CDRW, but with 6CD changer, you can put 6CD-R's with quite a few songs. And if you got the NAV system, I think there is a DVD drive then, so you can make an audio DVD-R which will hold a bunch.
I am a little confused though, because I think my factory '01 Civic had support for CDRW's. Because I remember burning tons of songs over and over onto 1 lightscribed disk. Maybe they took this off for some unknown reason.