When Apple announced the iPhone 5's new Lightning connector, a replacement for the 30-pin connector of past iPhones, iPads, and iPods, it also announced an adapter to maintain compatibility with 30-pin accessories and docks. I tested the iPhone 5 with its biggest 30-pin accessory, a Volkswagen.
Volkswagen uses the same iPod integration system as Audi, which it calls the Media Device Interface. This system consists of a proprietary port in the car with adapter cables for 30-pin iPod connector, USB, Mini-USB, and auxiliary input. As Volkswagen has not come out with a Lightning cable for its Media Device Interface, you have to get Apple's 30-pin-to-Lightning adapter, and connect it to the car's adapter cable. Not exactly an elegant solution.
I previously tested the iPhone 5 in a Chevy and Nissan by plugging its Lightning cable directly into those cars' USB ports. In each case, the integration worked perfectly, showing the iPhone 5's music library on the car's LCDs and with no difficulty in playing music through the new digital Lightning connection. Obviously, Apple had made no radical changes in its music control firmware.
After plugging everything in the Volkswagen together, the result was positive. I could see the music library on the car's LCD, and use the stereo's controls to select music. Music from the iPhone 5 played through the car's speakers.
However, there was one problem more related to the iPhone 5 itself and not the adapter: Bluetooth audio streaming continually grabbed priority over the cabled connection.
I had seen a similar problem in past iPhones, but not to this degree. With an iPhone paired to a car that offers Bluetooth audio streaming as an audio source, Bluetooth tends to take priority over the cabled connection. For example, if I first plug the phone into a car, then start the engine, the subsequent Bluetooth connection made by the car's stereo takes sole possession of the audio stream from the phone. Switching to iPod as the audio source, the car shows the music library, but there is no audio. My workaround has been to let the car establish its Bluetooth connection to the phone, then plug the phone into the car's iPod integration port. This method makes the audio stream available to either connection, and has worked in a wide variety of cars.
I used this method in the Volkswagen with the iPhone 5, letting it establish its Bluetooth connection, then plugging the phone into the adapter. But in this case, the car's stereo frequently switched to the Bluetooth streaming-audio connection of its own accord, even as I pushed the button to choose the Media Device Interface as the audio source. It was frustrating.
I could find no settings in the iPhone 5 to set an audio priority for music playback to either Bluetooth or cable, so I assume the phone automatically gives Bluetooth the priority whenever the phone detects a paired device.
As I happened to be reviewing a 2012 Golf R for CNET's Car Tech channel, that was the car I used for this test. However, this Media Device Interface is common in a wide array of models from both Volkswagen and Audi, and should work in like fashion across the line.