You need to burn your CD with WAV format tunes. Most of the older CD burning software will automatically convert your tunes to that format when creating an audio CD. As you may guess, mp3s etc converted back to WAVs will maintain the slightly reduced fidelity of the compressed formats, but none of the size reduction.

What you're wanting to do, therefore, is a process of last resort that I would not recommend.

It makes much more sense to leave your compressed tunes as they are, and get an mp3-capable CD player. If you have a tape player in your car, you could pick up an inexpensive mp3-capable portable cd-player with/and a car kit and go that route. Total investment <$40.

For software, I'd recommend Goldwave, available on the web as shareware. You might need to upgrade to DirectX 8, but you'll be prompted and directed to a download site, where DirectX 9 is available.

For what it's worth, I just put 13 complete albums in mp3 format on a single standard CD-R, and I encode with the relatively high bitrate of 192Kbps. The best you could do encoding to WAV is about 20 songs on a CD. Need I say more?

Good luck
S