Nanomachines designed to exhibit controlled mechanical motions on the molecular scale present new possibilities of building novel functional materials. Single molecule fluorescence imaging of dye-labeled nanocars on a glass surface at room temperature showed a coupled translational and rotational motion of these nanoscale machines with an activation energy of 42 +/- 5 kJ/mol. The 3 nm-long dye-labeled carborane-wheeled nanocars moved by as much as 2.5 mum with an average speed of 4.1 nm/s. Translation of the nanocars due a wheel-like rolling mechanism is proposed and this is consistent with the absence of movement for a three-wheeled nanocar analogue and the stationary behavior of unbound dye molecules. These findings are an important first step toward the rational design and ultimate control of surface-operational molecular machines.