Abhipuru,
Even my pioneer car CD player skips only with audio CDs.
But its ONLY with hard bumps. Lighter bumps pose NO problem to it.
I ve seen PC drivers having rubber dampers to absorb the shocks/vibrations and probably the same is done in INSIDE CAR players too.
The reason why MP3 plays fine is this: The MP3 is a compressed format . The player lens mechanism reads a chunk of data, the onboard decoder buffers it and plays for a long time from this buffer before it needs to read another chunk. When the car is going over bumps the dampers DO reduce the impact by absorbing the shocks/vibrations. But if the bumps are hard enough, the lens mechanism skips, then the buffer DOES provide enough data for the MP3 decoders without running out of data. So even if the mechanism skips, the buffer provides the data and no pauses occur in music.
However, technically, if the mechanism is made to skip continuosly for a longer time then the same pauses can be observed. To observe the same skipping phenomenon with MP3, you will have to take the car over a series of bumps continously for a longer time. For some time, the mechanism will skip and the buffer will provide the data to the decoder. After some more time, buffer will run out of data and the mechanism will still be skipping and the result will be that the decoder will have no data to play. You WILL find the audio muted in this case too.
The fact that you may not be able to find so many bumps together to observe this is tankfully another matter.
CD audio format is a different matter: It is uncompressed and the SAME buffer will be used to accomodate the uncompresed data. The decoder plays the data more frequently from the buffer and so the mechanism needs to fetch data more often to fill the buffer. If the mechanism skips and the meanwhile buffer runs out of data the audio is muted by the decoder. Due to the frequent filling/emptying of buffer this effect occurs very easily over bumps.
Though it is strange that your player skips on the slightest bumps. Do cross check again.
I doubt these players have sufficient buffers for CD audio since the primary music format in car is MP3. Never seen any user guides which speak of such buffers making my belief stronger.
Hope it explains your findings.
Goldy