So I have a 15' iSport Hatch and every time I start the car and begin to accelerate three clicks can be heard which seem to come from the roof of the car. At first it sounded like twigs falling on my car from trees but now I've noticed that it always occurs after the car is turned on and moves (does not occur at stops or stop lights). This leads me to believe it is something engaging, but I really don't know. Airbags maybe?
Do you accelerate quickly or does it also occur under heavy braking? I wonder if it might be a loose cable bouncing around in the roof, if you have a sunroof or satellite radio.