If we believe DW, then the reason he pulled into the Shell station is because Danni flashed her lights in relation to the missing phone. Everything he did after that is related to searching for a missing phone, and then searching for the owner of the phone. After 3 days of no contact with the owner of the phone, he phoned JDT just before he submitted the phone to police.
It seems too coincidental that a random bad guy opportunistically saw her at her only vulnerable moment, disabled her GPS and then she and her car disappeared. Seems far too organized for a random event.
JDT said that Danni and Car 3 left in different directions and that her car when to a heavily populated area. Assuming that DW is telling the truth, why did Danni go from "driving" her car to "occupying" her car at the moment that her GPS is disabled?
If this is not a random event, then either Car 3 had access to her GPS, or they followed her from The Dublin. Her car was easy to spot with the paper tags. Danni may not have been driving her car when it left the Shell station. The two drivers may not have gone in the same direction, but Danni was occupying one of the two cars.