I currently have a transmitter that you plug onto your phone (via 3.5mm jack) and then select a frequency on the devise.
Then on your car radio (or any radio) you select the same frequency as the one on the devise and it picks up whatever the device is playing. The range is decent as we were in convoy down to Durban last year and had three cars tuned in to the same station, listening to the music off of one phone.
The down side is that in Joburg there is a radio station every .2 of bloody frequency. So you never really have a quiet spot to tune to. There's always bad quality of radio jabber picking up somewhere.