iOS 4's hidden "iPod Out" feature brings iPhone support to your car without the messy third party UI

Cars touting full integration with the iPod and iPhone are nothing new — but so far, the experiences have been pretty terrible. The head unit (otherwise known as the “deck”) is tasked with pulling your music library from the iPhone, displaying all that data in a custom (and generally awful) interface. Everyone from JVC to BMW has taken it upon themselves to invent the wheel for themselves, and no one seems to have really nailed it.

Apple, it seems, wants to do away with these greatly varying interfaces once and for all. Lurking deep in the underpinnings of iPhone OS 4 is a feature that went almost entirely unnoticed until now, with BMW announcing support for it in their namesake and Mini series cars: a brand new, standardized iPod interface for use with in-car displays.

The idea isn’t too crazy: your iPhone/iPod Touch obviously already has access to your music library and knows how to handle it, so why not let it do the heavy lifting? The user interface is all rendered on the device, and then it’s piped out (along with your tunes) to the head unit via a standard docking cable. Car manufacturers have the ability to send control commands through external controllers like steering wheel buttons and separate control wheels.