So I scoured the site for a similar post, but couldn't find one. Today, while watching the series for the umpteenth time, I looked up during the scene when Michonne is tied to the post outside of the hotel. I noticed in the background, the light tan Ford Taurus station wagon, with the storage box on top, aka Ana & Sam's car, which became Carol's car. I don't know if that was just a prop car they put in the lot, or if indeed Ana & Sam were there, or if they eventually found the car.

I'm guessing it was just the prop car that was on hand, but it was a totally random find.