In the parametric optimization of an accelerator or a cruise vehicle for hypervelocity missions, five elements of the analysis relate to (i) vehicle configuration, (ii) weights, (iii) trajectory, (iv) propulsion and (v) control. A scheme for the overall system optimization is described. Considering weights, the concept of fixed weight growth factor in relation to gross weight is developed to illustrate the implications of technology development and staging. The analysis of the propulsion system must be based on both energy and energy availability considerations in order to assure not only the highest thrust and propulsive efficiency but also the least dependence on obtaining each component to operate at the highest achievable mechanical efficiency. A few propulsion schemes have been analyzed to illustrate methodology and benefits.