We review the history, current developments, projected future trends and environmental impacts of automated vehicles (AVs) and on-demand mobility, and explore potential synergies. Many automobile manufacturers and Google plan to release AVs between 2017 and 2020, with potential benefits including increased safety, more efficient road use, increased driver productivity and energy savings. Estimates of AV energy use and greenhouse gas (GHG) emissions range from an ~80 % or greater decrease to a threefold increase; however, we argue that net decreases are likely. On-demand mobility services exist in many cities around the world, with advances in mobile technology increasing their popularity. On-demand mobility can provide numerous transportation, land use, and environmental and social benefits, and users tend to decrease both vehicle ownership and annual vehicle distances traveled. Combining on-demand mobility and AVs may amplify adoption of both, and further lower energy use and GHG emissions through the use of small, efficient shared AVs.