1957 Jurisch Motoplan
Offered by RM Auctions | Madison, Georgia | February 15-16, 2013
You can kind of see it, but this car was actually built around a motorcycle sidecar. It was built by Carl Jurisch of Altdorf, Germany. From 1957 through 1959, he turned out three examples: one red and two blue. This is the only one known and it has a 173cc single-cylinder making 9.5 horsepower. Top speed is 54 mph. Read more here.
Update: Sold $103,500.