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In 2008-2009, EPA and DOE tested fifteen 2008 model year Tier 2 vehicles on 27 fuels. The fuels were match-blended to specific fuel parameter targets. The fuel parameter targets were pre-selected to represent the range of fuel properties from fuel survey data from the Alliance of Automobile Manufacturers for 2006. EPA's analysis of the EPAct data showed that higher aromatics, ethanol, and T90 increase particulate matter (PM) emissions. EPA focused their analysis only on the targeted fuel properties and their impacts on emissions, namely RVP, T50, T90, aromatics, and ethanol. However, in the process of fuel blending, at least one non-targeted fuel property, the T70 distillation parameter, significantly exceeded 2006 Alliance survey parameters for two of the E10 test fuels. These two test fuels had very high PM emissions. In this study, we examine the impacts of adding T70 as an explanatory variable to the analysis of fuel effects on PM.

This is the second of two papers that examine the future effectiveness of the California greenhouse gas “GHG” program and the federal fuel economy program established in the Energy Independence and Security Act of 2007 (“EISA 2007”) in controlling greenhouse gases. SAE 2008-01-1852 estimates the fuel economy levels that the California and federal programs can be expected to require, under assumptions stated in that paper. This paper applies those fuel economy estimates to examine the impact of the California and federal programs on lifecycle emissions of GHGs and carbon dioxide (“CO2”). EISA 2007 not only proposes to improve car and LDT fuel economy, but it also proposes to reduce GHGs through its Renewable Fuel Standards (“RFS”) provisions, which are likely to lead to substantial expansion in the use of 85% ethanol gasoline blends (E85).

The Environmental Protection Agency, National Highway Traffic Safety Administration, and California Air Resources Board released the joint mid-term Technical Assessment Review of the light-duty GHG standards in July of 2016. The review generally asserted that the GHG standards adopted in calendar year 2012 for 2022-2025 model year vehicles were feasible. Although many different technologies were evaluated, the review did not assess the benefits of high compression ratio engines enabled by a high-octane low carbon fuel. This study fills in the gap in the Technical Assessment Review by examining the impacts of a 98-research octane number gasoline-ethanol blend with 25 percent ethanol. We find that this fuel would enable higher compression ratios to improve tailpipe greenhouse gas emissions by about 6 percent on most engines.