Sorry to burst any bubbles but there is no power to any 3.5 jack that i am aware of in any spec. The 3.5 that you are referring to as 3.5mm audio jack is just right + left + common ground audio source. Some have more then 3 pins but that is not the norm and will not be supported by the standard for a car or any universal 3.5 spec aux input jack.
Also by adding in Bluetooth into the mix you will be loosing audio quality as bluetooth does not have a very high bandwidth so the data has 2 be compressed so u loose quality.
Your best bet is to use the big brick adapter that came with the touch pro that has the 3.5mm audio jack with the usb/power jack on it this will allow you to charge the touch pro and send audio out into the cars 3.5mm jack while only requiring one power source, any usb cable that can be plugged into a usb power source will work, like those cheap 12v usb car adapters that plug into your cars lighter/12v outlet that have a female usb socket on them.
So you would end up with something like this requiring only one connection to be made to the touch pro and thats the stock multi adapter to be plugged into the touch pro it would be getting power and sending music into your car (providing you leave the male to male 3.5mm cable plugged into the adapter and the cars 3.5mm aux jack, Leave the usb cable plugged into the power source and the multi adapter.)
