Is there a way to add a usb port to play mp3's to your car radio without having to install a new one that comes with a usb port?

Yeah, my mom uses something that looks like an audio cassette – let me see if I can find it.

link

edit: I think that’s what she uses…don’t buy it without making sure it’s what you need, heh.

I’ve also seen people use something similar to what @FutureMemory has said.

Is there a particular one that’s better to use over others? I have one but it’s super old and I don’t think it works.

Those cassettes don’t last long, and there’s really no way around that. Be prepared to replace it every… year or two, I think.

Get an in-car FM transmitter and you can listen to your MP3 player through the car’s radio. No wires necessary.

These are legal in the UK, not sure about anywhere else

@meiosis They’re legal in the states, but the quality is really, really poor.

USB cigarette lighter?
http://www.amazon.com/Cigarette-Lighter-Adapter-Players-Charger/dp/B000CC6I5W