My iPhone 5c will not play music through aux cable in car

I have recently changed my phone from an iPhone 4S to a 5c. Before the change, I would use my iPhone 4S to play music through the car speakers using an aux cable plugged into the headphone slot. However, my 5c won't play through the car speakers, instead it just plays from the phone speaker despite being connected by aux cable. I have tested the aux cable with phones of friends (iPhone 4S) who have been in the car and it works on theirs. My 5c plays music perfectly off my headphones, it's just with the aux cable that it doesn't work.

Why has this happened? Do I need a special type of cable? Or do I need to alter some settings on my 5c.