This research team envisions that connected testbeds, i.e., remotely accessible testbeds integrated over a network in closed loop, will provide an affordable, repeatable, scalable, and high-fidelity solution for early cyber-physical evaluation of connected automated vehicle (CAV) technologies. Engineering testbeds are critical for empirical validation of new concepts and transitioning new theory to practice. However, the high cost of establishing new testbeds or scaling the existing ones up hinders their wide utilization. This project aims to develop a scientific foundation to support this vision and demonstrate its utility for developing CAV technologies. This application is significant, because a synergistic combination of connected vehicles and automated driving technologies is poised to transform the sustainability of our transportation system; automated driving technologies can leverage the information available from vehicle-to-vehicle (V2V) connectivity in optimal ways to dramatically reduce fuel consumption and emissions. However, state-of-the-art simulation and experimental capabilities fall short of addressing the need for realistic, repeatable, scalable, and affordable means to evaluate new CAV concepts and technologies. The goal of this project is to enable a high-fidelity integration of geographically dispersed powertrain testbeds and use this novel experimental capability to develop and test powertrain-level strategies to increase sustainability benefits of CAVs. To realize this vision, the first objective of this research is to develop a cyber-integration interface to increase coupling fidelity in connected testbeds. This objective will be pursued through a model-free predictor framework to compensate for network delays robustly. The second objective is to leverage this cyber-integration interface to create a connected testbed for CAVs. To this end, existing powertrain testbeds distributed across the University of Michigan campus and Environmental Protection Agency will be leveraged. The third objective is to use this connected testbed for (i) developing powertrain-level strategies to minimize fuel consumption and emissions in CAV platoons of mixed vehicle types, including light-, medium-, and heavy duty vehicles, (ii) uncovering the untapped potential of aggressively downsized powertrains, and (iii) understanding the limits of the benefits of connectivity due to various V2V communication issues. This research area provides a rich space to advance the science of cyber-physical systems and demonstrate their impact, as it spans multiple disciplines including time delay systems, system dynamics and control, hardware-in-the-loop simulation, engine control, powertrain management, and communication networks. The potential of CAVs to improve the sustainability of transportation is an outstanding example of how cyber-physical systems can have a societal impact. The connected testbeds concept, on the other hand, can benefit not only CAVs, but also a wide range of applications such as telerobotics, haptics, networked control systems, earthquake engineering, manufacturing, and aerospace. It can open new doors for researchers to perform unparalleled integrative collaborations by enabling them to leverage each other's testbeds remotely.