How to sync an iphone to a mercedes for music?

I have a 2013 slk 250 mercedes and the iphone 4s. I want to be able to listen to the music on my phone in my car, how do i do it?

UMI,(universal media interface) or the NAV +4 is the only "Bluetooth Interface" that supports MP3 audio streaming. So unless you have one of those you won't be able to unless you get some sort of a third party accessory that allows you to do so.