Wang, Michael Q., David L. Greene, Mark A. DeLuchi (1991) Effects of Increasing Fuel Economy on Gasoline Vehicle HC Emissions. Institute of Transportation Studies, University of California, Davis, Presentation Series UCD-ITS-RP-92-03
Emissions of gasoline-fueled passenger cars and light-duty trucks (LDTs) accounted for 24% of total emissions of volatile organic compounds (VOCs) in 1988 nationwide. Various control measures have been considered to reduce vehicle HC emissions and help attain the national ambient ozone standard; stringent tailpipe standards, on-board vapor recovery system requirements, lower Reid vapor pressure (RVP) of gasoline, use of clean-fuel vehicles, etc. The Office of Technology Assessment (OTA) estimated that costs of these measures ranged from a little less than $1,000 to $39,000 per ton of VOC reduction. Improving vehicle fuel economy may also reduce HC emissions, but this possibility has not been thoroughly analyzed.
A 1983 EPA study which analyzed the relationship between fuel economy and vehicle HC exhaust emissions did not find a significant relationship between fuel economy and HC exhaust emissions. However, the study did not include vehicle HC evaporative emissions.
In this paper, we estimate the relationship between fuel economy and HC emissions for each of four sources: tailpipe, diurnal evaporation, refueling evaporative losses, and running evaporative losses. Using the estimated relationships, we analyze changes in HC emissions due to fuel economy improvements.