As a precursor I have searched for this topic and come up empty on several occassions. I have an 04 Mazda 6s MT and I have noticed that the steering column makes a very loud clicking only when the vehicle is pointed straight and only when the vehicle is in motion. Previously it made a clicking sound when turning the wheel back and forth - however the dealer fixed that by replacing a clock spring. I don't mind the occassional rattle that vehicles have, but this one is bugging me as I fear it might be symptomatic of something larger. I have also tried moving around the telescoping wheel in different positions to no avail. Also, the rattle/clicking sound does not occur when the steering wheel is turned off center even by as little as five degrees (on ramps or gradual turns on the freeway). The rattle only happens when the car is pointed straight ahead. One last thing it is loud enough to hear over the radio while on the freeway.
Any ideas or thoughts would be greatly appreciated. Thanks