That amazon link posted was an mpow Bluetooth receiver. It's a box that receives Bluetooth and outputs it to a headphone jack. If you connect your phone to it it will transmit the audio over Bluetooth and output it to a headphone jack.So I just search for mpow transmitters? Any price range I note? Any good brands?
You'd usually use an aux cable and plug it up to your car but if you don't have an aux cable you can use a fm transmitter and set that you a certain radio station and pick it up from your car's radio.
Or you can get an fm transmitter and use the lightning to 3.5mm dongle for the same effect.
I bought this one. Works great.
I don't need the fm transmitter because my work car has an aux. I'm my personal car I just bought an new radio with built-in Bluetooth and installed it myself.