If JM was driving the car he had yesterday since his was impounded, is it possible that LE got a warrant to put a tracking device on it. LE was not secretly tailing him, according to Longo, it was obvious they were there. So LE made a show of following JM and then letting him get away when it is too reckless. But they actually know where he is.
The fact that LE did not release the description and license plate info of the car he was driving recklessly or where exactly they gave up following it makes me think that they are aware of where he is. They are not asking people to be on the lookout for that car.
Perhaps they want JM to think they don't know where he is and follow his movements secretly. Like Scott Peterson.