The Martian soil type, slope, and rock size distributions and moisture content are similar to those of the American West. Notable exceptions include significantly reduced gravity, wind pressure, water content and temperature. Previously published pictures of Mars Rover designs proffer concepts unlike those of conventional earth-based vehicles. Novel mobility systems, including jet planes, bag wheel axles, walking machines, articulated wheeled and track modules, balloons and dirigibles have been suggested. The locomotion systems of these vehicles are compared on the basis of energy utilization (mileage) and mobility. A novel single track crawler is described. Steering of the single track crawler is accomplished with a laterally flexible track and cable system.