I've never been to Spring Fling -- are you maybe talking about MoparFest? I doubt if I'll be going this year; I'll probably have already moved out West by then (or else I'll be right in the middle of the move).
I was thinking about driving the car back if I like it...so does that mean I have to stay down for three days?
No, that makes it much harder, both for you and for the seller. All the official importation paperwork has to be done at the border, and he who brings the car across the border is the importer (and therefore has to pay the duties etc.).