We investigate the effects of actuator and sensor bandwidths on robust stability of intelligent cruise control of autonomous vehicles with different feedback biasing strategies for two types of boundary conditions. The first one is a platoon of vehicles on an open stretch of highway, and the other one with periodic boundary conditions. The goal of the feedback is to maintain the same relative velocity and keep a certain safe distance between adjacent vehicles. We obtain in closed form the stability regions in the parameter space of the feedback gains for different biasing strategies of controllers. If there is biasing, it is shown that the two types of boundary conditions engender qualitative different stability characteristics: when the number of vehicles n is large, the robust stability in the case of periodic boundary conditions is much weaker than open boundary conditions. The spatially discrete model is approximated by a continuum model described by partial differential equations. The n-mode truncation of the continuum model and the spatially discrete model predict approximately the same region of stability for lower order modes, as well as the same qualitative features of overall stability region in the parameter space of feedback gains.