This deliverable provides a report of the work conducted in Work Package 12: eco-driving system development and HMI feedback. The tasks required development of simple eco-driving feedback model algorithms and test scenarios and an assessment of basic systems and feedback modalities. These assessments have been conducted both in the laboratory and the simulated vehicle environment. The output of this stage of the ecoDriver project has been used to inform the design of Work Package 13 studies which are focused on the evaluation of eco-driving feedback solutions. This Work Package represents an important stage in the design of the final ecoDriver system, which is currently being prepared for in-vehicle integration and on-road testing.