  This paper focuses on energy-efficient longitudinal controller design for a
connected automated truck that travels in mixed traffic consisting of connected
and non-connected vehicles. The truck has access to information about connected
vehicles beyond line of sight using vehicle-to-vehicle (V2V) communication. A
novel connected cruise control design is proposed which incorporates additional
delays into the control law when responding to distant connected vehicles to
account for the finite propagation of traffic waves. The speeds of
non-connected vehicles are modeled as stochastic processes. A fundamental
theorem is proven which links the spectral properties of the motion signals to
the average energy consumption. This enables us to tune controller parameters
and maximize energy efficiency. Simulations with synthetic data and real
traffic data are used to demonstrate the energy efficiency of the control
design. It is demonstrated that even with lean penetration of connected
vehicles, our controller can bring significant energy savings.
