This paper presents an architecture for cooperative driving of automated vehicles, which means flexible platooning including smooth merging and lane changing, in conjunction with experiments on a test track using some technologies for sensing, control, and inter-vehicle communications. The architecture consists of three layers: the vehicle control layer, the vehicle management layer, both of which are on each vehicle, and the traffic management layer on the infrastructure. The experiments illustrating the parts of the architecture include visual platooning by two automated vehicles, and fusion of the data through the inter-vehicle communications and the data of the inter-vehicle gap measurement.