Fairly extensive searching, here and elsewhere, has failed to throw up what I am looking for so please direct me if you know where the answer lies. I have a Bluetooth system built into my vehicle which is successfully paired with my iPhone. Running Navigon Mobile Navigator App on the iPhone is a real pleasure but I am seeking to increase the volume of the Navigon Voice Directions to combat road noise in heavy traffic on the motorways. The vehicle dealership tell me the installed Bluetooth kit cannot supply the functionality to route the Voice Directions through the vehicle radio. The current unit does not have an Auxiliary Jack or USB Connector. Does anyone have experience overcoming or resolving this problem? Items considered thus far: 1. Placing the iPhone in the corner between two hard surfaces improves the sound level dramatically, much like the AirCurve device available commercially. My thoughts are that perhaps a suitable plate, the width of the iPhone and about 175mm long, with the centre 125mm section remaining flat and the ends equally spaced curved gently upward will project the sound in the desired direction. This would need mounting to a suitable in car support. 2. The next consideration is an FM Transmitter, on manufacturer has confirmed that their product will do what I am asking. 3. Lastly looking at Bluetooth Headphones, although I am happy to accept a single Earpiece, one manufacturer has declined to recommend on driving safety grounds [I applaud the view to be as safe as possible whilst driving] and await replies from other suppliers. Any input or alternative ideas on the subject will be gratefully received.