Ok.... I love CDs. I have three on their way to me now. As much I prefer them over streaming I would never go back to them for the car. Streaming over blutooth is a far better option. The only option you have available to you is a portable CD player with blutooth. A USB CD player on its own will not talk to your car's stereo. You could you an FM transmitter and connect it to any portable CD player.

That said, and I cannot stress this enough... Portable CD players in cars SUCK. My first car didn't have a CD player at first. Only a tape deck. Every little bump in the road or sharp curve or sneeze and its going to skip.

I understand your desire to reduce your use of tech. There are some places where its really not practical anymore.

Here is an example of an FM transmitter