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MP3 CD players work quite different from standard audio CD players. With playing a regular Audio CD, the laser pick-up head starts at the beginning (or the initial selected track) and continues reading until the end of the disc. Since all the tracks are physically joined (like a record), it is possible to have gapless playback on an audio CD. The table of contents on an Audio CD basically marks the start and end points of each song.
MP3 CD's store music in individual files and tracks are not necessarily stored in the order of the table of contents. This means when the CD player finishes playing an MP3 track, it must fetch the next file on the CD, buffer part of it to begin the decoding process and start playing the new track. As a result, this may result in a few seconds silence between tracks.
I am not sure if MP3 capable car stereoâ€™s can pre-buffer the upcoming track for gapless playback. One way to check for this is to rip a CD with tracks that have no silence between them, convert the tracks to MP3, record them to a data CD-RW and if this CD plays with gaps between the tracks in the car stereo, then unfortunately there is no way to eliminate the gap between tracks for your stereo.
One way to help reduce the amount of silence between tracks is to cut excess silence from MP3â€™s using an MP3 editing tool such as MP3DirectCut.