CRC Vehicle Emissions Program (2015): Effects of 85 and 87 Anti-Knock Index (AKI) Gasoline Ethanol Blends on U.S. Light-Duty Vehicle Emissions, Fuel Economy, and Performance at Two Elevations (1,000 ft. and 5,000 ft.).

摘要

This Program investigated the effects of gasoline anti-knock index (AKI1) on vehicle fuel economy, tailpipe emissions and engine and exhaust performance parameters for a fleet of nine model year 2008 – 2013 passenger cars and light duty trucks. Three different vehicle chassis dynamometer laboratories, each possessing variable altitude, temperature, and humidity controls, performed a total of 305 vehicle tests over the course of nine months. Two test fuels, closely matched in composition and energy content, however differing in their AKI value (87 and 85 AKI) were tested. The vehicles were tested under two simulated elevations: 1,000 ft. and 5,000 ft., (305 and 1,524 m). Each fuel, vehicle, and elevation combination was tested a minimum of two times using three standard US and California vehicle tailpipe emissions test cycles: US FTP-75, LA92 Unified, and US06. The test cycles were chosen to investigate the effects of a range of driving styles and severities on vehicle octane requirement. Statistical analyses of the nine-vehicle-fleet means, individual-vehicle means, and correlation to vehicle attributes were conducted. The test program methodology of using standardized emissions test cycles to evaluate fuel octane number effects on vehicle response was a good approach to gain understanding. The use of a range of emissions test cycles enabled the evaluation of trends in vehicle response and showed driving style is important with respect to the impacts of fuel octane number.