On Friday, September 23, 2016 at 11:46:16 PM UTC-4, wrote:
On Fri, 23 Sep 2016 23:09:29 -0400, John Albert
wrote:

On 9/23/16 5:51 AM, wrote:
But what about car radios that have a CD player. Is there a similar
device that can be pushed into the CD opening to allow another audio
source to be played, such as a MP3 player?

Depends on the vehicle, but most newer cars have at least
one of the following:
- Auxilliary input jack
- Bluetooth
- USB port.

My 97 Honda did not have the aux jack so I used a cassette adapter or
an FM modulator. (Tried both). It was OK but eventually I just bought
another radio with the jack. Same with 2002 Ford truck.
There was a hack around for the Honda using the DIN plug for the CD
changer but I did not try it.

That hack now uses the XM Radio DIN connector. BTDT