I am aware of the differece between firewire car charges and usb ones. I have another problem and am not sure if it is my new phone or something else. I use my phone through a mini jack to play in my car stereo. Everything works fine until I plug in the car charger, as soon as it is conected to the power source I start having trouble. It charges, but cuts the audio output. If I use the Ear buds it doesnt seem to effect the audio. Anyone have any ideas? The appholes at the store have no clue.