Did you try turning the volume of your mp3 player up high to see if there's a problem? Sounds to me like a deficiency in your car player or speakers. Turn the equaliser down & see if it still has that effect. It might be a super bass line that your speakers can't handle when put thru the equaliser. But then again, clipping is usually a recorded peak that's too high. Normalising the songs as a whole might fix it. It depends where the problem lies. Do you have a player where you can see the volume levels? A software player or editor would be good for checking to see if the levels are too high. If you don't have one, get http://audacity.sourceforge.net/windows.php which is free. It can also open mp3's, etc. And you can open a file from an audio cd.

I don't know about windows, but on a mac, you can get a selection of songs together you want to put to CD, open them together with Jam, then normalise as an overall album. Else save it as a Jam disk image, then open with a program like Peak & normalise the entire amount to the level of your preference such as 80 or 90% of maximum (of safe level.) Then save, open with Toast & burn.