Could you be more specific when you say noise? I can see a couple different sources you may be talking about.
1. Burning a CD: I've burned CDs before where the data buffer was toast durring most of the burn. This created massive noise on the CD. It's possible that a similar thing happened, where the CD itself has the noise on it because of a poor burn.
2. I'm sure sound quality is good in the car, although I can't attest to this personally because my inverter creates so much noise the setup I had was impossible and I've ordered an Opus. While the sound quality in your car will also depend on the components you've hooked the computer up to. If the quality wasn't good, some of these guys just wouldn't build these computers. I'm not an audiofile, but I like clean music, some of these guys don't listen to MP3s with a 128k bit rate because it's too low for them.