A virtual wheel provides a leg pair as a conveyance mechanism for a land vehicle. The virtual wheel propels the vehicle across a surface using a repetitive motion of the legs that contact the ground as would a wheel, due to their geometry. Vehicle embodiments include at least two-, three-, four- and six-wheeled vehicles, both transverse and in-line. Additionally, the invention provides a bipedal walking robot. One embodiment provides a robotic mule--a payload-carrying vehicle. The invention combines the flexible mobility of bipedal vehicles with the stability and functionality of very large-wheeled vehicles. Additionally, a bimodal conveyance mechanism readily converts between walking and rolling modes