If it doesn't sound good as a WAV file, it ain't gonna sound better as an MP3. The MP3 is a compressed version of the WAV file (to put it simply); some sound variation in samples is lost for compression's sake, but it isn't anything your ear will notice (in the higher bit-rate quality MP3s... 128kbps and above. So don't expect converting it to MP3 will solve your problem.

Do regular commercially-made CDs play alright in your truck player? erhaps it's an issue with the CD-R itself (or are you using a CD-RW; though that likely won't play at all). Or make sure you are using the proper settings to record your WAV file: CD Quality (16 bit, 44100Hz, stereo)

And Foolestroupe, I do indeed have an old download of CoolEdit96 here. It's almost 2 megs in size. PM me your e-mail address and I'll send it to you.