We have investigated by STM the controlled molecular motion of individual molecules on surfaces through the rational design of fullerene- and carborane-based nanostructures. The NanoCar molecule (four fullerene wheels connected by rotating alkyne axles to a central chassis) and the related molecular structures are designed and fabricated specifically for nanoscale manipulation. Our work has consisted of characterizing by variable-temperature microscopy and manipulating these molecules using the STM tip to probe the effects of surface-molecule interactions on the direction and speed of motion. This family of molecules is all built from a similar set of "molecular tinker toys" that includes interchangeable components for "chassis," "axles," and "wheels." The results of these studies underscore the ability to control directional motion in molecular-sized nanostructures through precise molecular synthesis with possible applications to surface catalysis and nanoscale tribology.