  In the near future, our streets will be populated by myriads of autonomous
self-driving vehicles to serve our diverse mobility needs. This will raise the
need to coordinate their movements in order to properly handle both access to
shared resources (e.g., intersections and parking slots) and the execution of
mobility tasks (e.g., platooning and ramp merging). In this paper, we firstly
introduce the general issues associated to coordination of autonomous vehicles,
by identifying and framing the key classes of coordination problems. Following,
we overview the different approaches that can be adopted to manage such
coordination problems, by classifying them in terms of the degree of autonomy
in decision making that is left to autonomous vehicles during coordination.
Finally, we overview some further peculiar challenges that research will have
to address before autonomously coordinated vehicles can safely hit our streets.
