I saw this happen at a Staples! They were fitting a huge desk set into a similar-sized car. I asked them where they were headed and they gave a location like 20 miles away that the main route is via I-95. I assume that they made it, but man oh day.
Seriously, I can't think of a modern vehicle that doesn't have fold down rear seats, could have just slid it into the trunk.
that was my thought. Hell, even if the seats don't fold down, I'd slide that sucka up so deep in the trunk, the sky be cryin'. (<-- Old web humor reference) and then use the rope to tie down the trunk lid.