Here is something everyone can do to get trouble free transmission from your N900 to car radio. Either unscrew the whip or push down the antenna (depending on the type of radio antenna fitted) or try the following... what is needed is a simple switch to disconnect the antenna wire from your radio, the centre wire in the coax of your antenna lead going to the actual antenna on your car, what this will in fact do is stop the antenna from working and will give you a quiet radio that will pick up the local transmission from your N900 as it will be in the car without any interference from an outside broadcast. Worth a try.