Simultaneous Measurements of Driveability and Emissions at Cool Ambient Temperatures

Simultaneous measurements of cold-start/warm-up driveability and tailpipe emissions on a chassis dynamometer were made at 5°C using four late-model vehicles. Two fuels wore used: a low driveability index (DI) fuel containing 11% MTBE and 29% aromatics, and a high DI fuel with no MTBE and 43% aromatics. Tailpipe hydrocarbon emissions and total weighted driveability demerits (TWDs) both correlated with the fuel used; both increased significantly when high-DI / no-MTBE fuel was used. A strong linear relation exists between TWDs and simultaneously measured tailpipe hydrocarbon emissions. CO and NOx emissions did not correlate with fuel composition.