  We introduce a novel distributed control architecture for heterogeneous
platoons of linear time--invariant autonomous vehicles. Our approach is based
on a generalization of the concept of {\em leader--follower} controllers for
which we provide a Youla--like parameterization while the sparsity constraints
are imposed on the controller's left coprime factors, outlying a new concept of
structural constraints in distributed control. The proposed scheme is amenable
to optimal controller design via norm based costs, it guarantees string
stability and eliminates the accordion effect from the behavior of the platoon.
We also introduce a synchronization mechanism for the exact compensation of the
time delays induced by the wireless broadcasting of information.
