Remember, they had to get a subpoena to get Sunpass toll records. That was 7/16/2015, according to the PC. Right around your article came out. For the subpoena, they had to submit the cell site data of phones used by Garcia and Rivera to the Florida Department of Transportation. How did they get the cell site data without knowing who Garica and Rivera are? I don't see how their identities could not have been known by then. Perhaps they were considered just suspects then and TPD thought other leads (orthodox Jews and unhappy law students) may have been legitimate. We don't know for sure and they may have known just their cell numbers by that time. Remember, they didn't approach the rental company until they got the subpoena, which was after 7/16/2015, after the article came out. Those are inferences from the PC and articles that have come out since. Like I said, I could be wrong if any of the facts are wrong. But I tend to think the reasoning is sound.
I've been wondering how they made the leap from the fact that it was a Prius to these two specific individuals if the license plate wasn't visible in the videos. I wonder if it was cell tower dumps--get a list of all phone numbers that interacted with the tower serving the location where the Prius was spotted at a specific time and bump that against lists from other times and towers from other times the Prius was spotted.