SignalTrace can link device signals to your car

Your phone may be giving a roadside sensor clues about where you go and which devices regularly travel alongside you. Say you carpool to work with the same person most mornings. Your car passes a license plate reader, which records the plate along with the time and location. Meanwhile, another sensor detects wireless signals coming from devices traveling nearby. Your phone might be there. So could a smartwatch, wireless headphones or electronics built into the car.

After enough trips, software...