I would imagine there is a good bit of carpooling to conserve fuel and free up space for trade goods. Not to say all the PCs will share vehicles, but most members of the tribe would share rides. We can assume for now that at least one NPC normally rides with her when they're on the road. If you and Laura want to say that Searle normally rides with her when he's not on scout duty or driving the guard van that's fine too.