Talk about being parnoid, the rooftop antenna is just that providing function for tel aid if you have it, and a cellular antenna in one unit. I you did not retrofit your analog tel aid 2001 to 2005 to digital you have no tel aid. The same goes for telephone which was analog. The GPS signal from tel aid aided in determining your location, and was interfaced with your door lock system to provide remote unlocking. There was also a backup antenna in case you rolled over the car and broke the antenna. as ar as I know there was no further communicatin with the power train and body electronics, and if you did not retrofit a newr tel-aid system there is no communication.
By the way you pocket cell phone can also track you....