A good design requires knowledge of the inputs to the system as well as a means of evaluation of the result. For cross-country vehicle speed limits due to the vehicle's vibrational activity, the terrain profile becomes the important system input. A statistical technique for classification of this input has been developed and is presented as an analytical expression. With this definition and standard mathematical modeling techniques, a tool can be developed for aiding in the concept phase of the design process. Vehicle design trends for better cross-country speeds are discussed in terms of improving the ride comfort of a vehicle asevaluated in this way. Hardware examples of vehicle improvements are discussed.