Hello, I have only just heard about this; I don't know too much... but from what I have read, here is what I think.
When he was sitting in his car just plainly staring into nowhere, repeatedly picking his phone up and just telling his parents that he would start coming home, that bit intrigued me.
He definitely wanted to be left alone. I think he was waiting for someone and he was just waiting a long time; perhaps he was waiting for there to be absolutely no one in sight. That's why he was in his car for so long. Maybe this meeting with this person was that explaining what he told his parents he was going to do. Regardless, as he was forced to go back by the mechanic, he pretended to take that nap and purposely crashed his car. Then he would make his way to that truck station and possibly come back to that same spot and meet with the potential someone. (It is a bit far fetched but possible). The car crashing would probably make it harder for people to find him, hence, the countless other theories. I wonder if the person in the truck was either a stranger or a potential somebody.
Alternatively, I don't know about the geography of where he was, but there could have been a place like a cliff, lake etc. That he was going to suicide in, or a route he was going to go on and get off the grid, but, he was just waiting for no one to be in sight, so there would be no witnesses. Please let me know any crucial details and flaws with what I said; I feel bad for this kid
![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)