The equalizing of MP3 volume level is something your AudioCD creation tool may provide. You didn't tell what you used, so I can't tell you if it has such.
this might be a dumb question but i hope someone can answer it. last night i created a playlist of individual songs and burned a cd. my question is that when i popped the cd in my car i had to turn the volume up higher than i normally would for any cd. i remember having the volume slider on the media player set to a lower volume (was burning at night) when i was burning the cd. would this have had an effect on the volume level that the cd was burned at? should i go and burn another cd with the volume level (on wmp 9) set in the middle or a slightly higher setting? any help would be greatly appreciated.