We present a simple smooth time-varying formation controller for autonomous vehicles, both in leaderless and leader-follower scenario. The controller is efficacious for scouting missions in which a group of robots is required to meet at a specified rendezvous location and acquire a non-specified consensual orientation, with the purpose of advancing in formation at the pace of a virtual leader. Hence, the controller that we propose achieves stabilization in Cartesian coordinates and consensus in orientation, for robots interconnected over generic directed graphs. To overcome the effect of the nonholonomic constraints it relies on persistency of excitation.