  Platoons of autonomous vehicles are being investigated as a way to increase
road capacity and fuel efficiency. Cooperative Adaptive Cruise Control (CACC)
is one approach to controlling platoons longitudinal dynamics, which requires
wireless communication between vehicles. In the present paper we use a sliding
mode observer to detect and estimate cyber-attacks threatening such wireless
communication. In particular we prove stability of the observer and robustness
of the detection threshold in the case of event-triggered communication,
following a realistic Vehicle-to-Vehicle network protocol.
