On February 15, 2018, the U.S. Department of Energy (DOE) announced the release of the Co-Optimization of Engines & Fuels (Co-Optima) report titled Fuel Blendstocks with the Potential to Optimize Future Gasoline Engine Performance (Fuel Blendstocks report), along with the companion report on Efficiency Merit Function for Spark Ignition Engines. The Fuel Blendstocks report identifies eight blendstocks that have the potential to improve gasoline performance. The assessment criteria included physical properties, high-level health-impacts, the ability to improve advanced spark-ignition engine efficiency, and the potential to be introduced commercially in the 2025-2030 timeframe. According to the report, a targeted effort was made to identify fuel components that can be sourced from domestic biomass. In addition to increasing U.S. energy security and creating jobs in rural America, use of renewable fuel components can provide technical, societal, and environmental benefits. Part of the Co-Optima objective is focused on developing data on blendstock production, fuel properties, and engine performance to perform a detailed assessment of the benefits of sourcing blendstocks from biomass versus conventional resources, and to identify areas where further research and development are needed. During the next phase, Co-Optima will validate the potential fuel efficiency improvements through engine testing and will also begin examining fuel efficiency gains in heavy-duty diesel engines.