There is a clear and growing need to more efficiently utilize conventional petroleum- based fuels in internal combustion engines. Significant improvements in engine efficiency are possible through the use of fuel-derivatives, exhibiting desirable properties, such as high octane or improved evaporative cooling capacity, among others. Production of different fuel streams off-line is impractical, costly, and unsupported by existing infrastructure. This DOE SBIR Phase I project aims to evaluate the feasibility of on- vehicle generation of fuel-derivatives to supply high-quality fuel components with desirable combustion characteristics to the engine on-demand for improved efficiency. The specific project objectives are to: Design a system for low-cost, small form factor, on-board separation of ethanol and ethanol derivatives from petroleum fuels, and complete a systems analysis and select the most promising approach to supply high-quality fuel derivatives to the engine on-demand, for testing and evaluation in Phase II If successful, the results will form the basis for developing a demonstration system capable of meeting DoE targets of 10% fuel economy improvement at a production cost of less than $200/unit to undergo engine evaluations together with commercial partners in Phase II. This project will leverage recent advances in fuel separation and reforming technologies currently being developed by FST and MIT. This development has resulted in several patents and patent applications covering both novel in-cylinder reforming methods, non-membrane based fuel separation techniques, as well as methods for reforming separated fuel components. Phase I will focus on a feasibility analysis and proof of principle for onboard fuel separation technologies, supported by bench and engine experiments. The approach is focused on reducing technology risk and addressing the key technical barriers early in the Phase I program. The commercial applications span the range of light-duty to heavy-duty vehicle applications, as well as industrial engines and processes. The primary societal and environmental benefits include reduced petroleum consumption and associated greenhouse gas emissions, as well as enhanced energy security. Commercial benefits include cost-competitive and highly-capable on-demand fuel delivery systems, providing significant fuel savings, in an inexpensive and robust system, suitable for a wide range of transportation applications. Aside from fuel savings, the technology may further allow for the use of less refined petroleum feedstocks in vehicles, by delivering the same high combustion efficiency through on-board fuel processing in future applications.