After reading the question Why are there no Micro USB to Micro USB cables? and related posts, I stil didn't find any answer to my case. I have bought a car radio that has the possibility to play music with an other device. The input for the car radio is micro USB. The device from which the music would be played is Nokia Lumia 625- in other words micro USB output again. So buying a micro USB to micro USB cable would work?
USB is directional, except for USB3.0 (bi-directional). However, still the USB specification requires one device to be master, other slave. plugging them other way around may cause damage to USB hub.
While I agree that lack of usb cabling is idiotic - I would LOVE to connect my external USB to my Galaxy S3, which is technologically possible, but without proper cabling this may cause issues - there is an issue with that: plug the cable into the wrong ends and you're possibly frying both devices (that is: USB controllers.
In other words: are you SURE you know which device of your two will be the host and which the peripheral? If you're not sure, maybe manufacturer is even less? Being sued for damage is not fun.
What you would need is a 2xType C cable, which is not available yet (I think). You can of course buy the cable and try, but I would not be bold enough to try, unless I can write off the phone, radio or both. I'm not saying it will happen, just that it will happen EVENTUALLY. Yes, the Micro-USB connector in a radio points to "On-the-go" capability, but I would make sure. Maybe it would be easier to connect the phone via headphones jack? Radio has to have AUX IN of some kind?