iPhone 6 - interference when cars drive by

I got the iPhone 6 (64gb, iOS 8.2) last month and since having it, several people I've called have reported a "clicking" sound -- both cell phone and landline users alike. The clicks happen approx. 5 times/seconds and are intermittent, not constant. I, fortunately, do not hear this interference. I've spoken with Sprint's tech support, have taken my phone to both the Sprint and Apple stores, and until now, have been unable to create this clicking on command.

Tonight, I figured out that the other person hears this clicking only when cars drive past my house. I've stood out on the sidewalk while on the phone and the other person has reported this clicking only when one or more cars pass by. This does not happen next to parked cars.

I'm assuming the interference is caused by the cars' computer systems/radio waves. Is there anything I can do to prevent the people I'm speaking to from hearing this clicking noise???