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You can get a AUX cable, then connect it to your phone and to the AUX input of your car. Then you can play the music on your phone directly and it will output through car speakers.
Or you can pair your S5 with your car via bluetooth. There is a feature named Car Mode on your phone. Refer this article --> http://visihow.com/Use_Car_Mode_on_the_Samsung_Galaxy_S5
Let me know how it goes