"Ah. That explains it. If it's a radio, then we'll only be able to listen in on a frequency, but we can't answer back." He lets Senku tinker around with it, but it's what Tidus says that makes Roland look around, peering out of the car with a tilt of his body towards the closed door.

"...That's definitely a must. But before that, how about an experiment? Take the radio in every car, check every dial it has, and see what we pick up? If at all?" He offers the solution, simple enough, to both of them with a finger under his chin in thought.