With a Bluetooth connection, the data exchange always takes place directly between the sender and the receiver. Both must have a corresponding chipset with an individual serial number for identification. If this is not the case, it will be at the expense of the connection quality... In addition, Bluetooth only provides a limited bandwidth for streams. Therefore, audio data for sound transmission is converted into the lossy codec SDC. This is at the expense of sound quality.
The constant connection that Bluetooth needs also requires a lot from the battery. To save your battery and to have a better sound quality, it is better to use a fixed connection. Especially with long rides and good music. Of course, you always want to be able to connect your cell phone easily. This is why Joli iPhone car mounts have devised a nice adapter that you can place out of sight in your cup holder.