The seller of the '04 GT I recently bought had installed an AUX input jack in the (stock) stereo. The jack is connected to an FM transmitter, so you can plug in a phone or other audio player and play audio through a radio station. He installed an on/off switch as well, connected to the transmitter. He said that he turned off the transmitter when not in use, because he was afraid of running down the battery. He said however that he wasn't sure if it would or not -- he just did it to be safe. Now, I am terrible about remembering to do this, and moreover I'm not sure (even less than he was) whether or not it's actually necessary. I of course don't expect a definitive answer to this question, since I can't say specifically what he installed or how, but would welcome any educated guesses: would the transmitter be likely to draw power from the battery when the switch is left on, even if the car is turned off entirely and/or the stereo is turned off? Thanks in advance for any feedback.