Remember that making a CD of a commercial dvd soundtrack is probably a Federal Offense and that is no joke. Look at how the RIAA is treating people when they copy songs plus you will get a higher quality CD if you just buy the CD.

Legal issues aside there are probably several ways to do what you asked.

How High Fidelity do you need to have for toolin around in your car?

First thought is play the dvd on your dvd player and put sound output into your pc to record the soundtrack on your PC's hard drive. You many have a stereo input on your audio card (depends on the card) or stereo audio input on your video card (depends on the card) or you can buy an inexpensive adapter that will take dvd audio output and input to your PC.

You can capture song-at-a-time or capture as one long track and then chop it up if you care to.

I would capture the sound as wav and then open that track in timeline of one of many editing programs and then slice and dice into tracks as you care to and then render the tracks as preferred format for CD burning - .wav or mp3 or whatever.

that's a lot of work so I'd just buy the CD if I liked the DVD so much.
GoodLuck