So given the 48 hour window and the fact that the Jeep hasnt been found, what is your best guess especially the locals? Where would you dispose of a vehicle...would you drop it off in downtown Chatanooga with the keys in it? I mean really, what would you do???
Interesting thought (dropping off with the keys in it.) If I were LE, I'd run the registration and VIN...and check those against every state in the continental US in the event it was stolen or sold. Then I'd start looking at the financing of the vehicle. Is it paid off? A loan? A lease? Who's name is associated with each vehicle in the household- or elsewhere anyone associated with the case is?
If I intended to harm someone who was fiscally and legally solely responsible for the vehicle, I don't think I'd have a problem sinking it somewhere in order to destroy evidence and make it appear as if the owner of the vehicle disappeared willingly- or, as mentioned earlier (if I knew there was no evidence of the vehicle holding clues to a disappearance) I might park it somewhere it wouldn't stand out if it sat for a few or three days.
If I had nothing to do with harming someone, but cared for them- I'd want areas of probable accidents searched, as well as areas of high crime, where a carjacking or theft might occur. I would want all locations that the person missing along with vehicle may have gone searched; including personal properties, properties of friends and family, and any frequently known areas visited by the missing person searched.
But if there were any financial or legal obligations to the vehicle that were associated with MY name, I think I'd go about it differently. I might trade it in. If I needed a relatively large sum of cash immediately, and I were in possession of the vehicle, I might either pay off a 'debt' with it, chop shop it, or sell it under the table to someone.
Lot's of possibilities, it seems.