This paper is the third in a series providing fuel blending and analysis data for the Auto/Oil Air Quality Improvement Research Program (AQIRP). Preparation methodologies, analytical techniques and fuel property data are presented for the Heavy Hydrocarbon/Volatility study and other programs not previously reported. Papers by Pahl and McNally (1)* and Gerry et al. (2) have presented information on the fuels of the AMOT (Aromatics, MTBE, Olefins, T90), Methanol, RVP/Oxygenate and Phase I and II Sulfur programs.The Heavy Hydrocarbon/Volatility fuel study was initiated in an effort to better understand the 90% distillation point (T90) effect observed in the AMOT matrix of Phase I. The study was comprised of two matrices and twenty-six fuels. The first eighteen-fuel matrix, designated as the “A” matrix, investigated the effects of medium, heavy and tail reformate and medium and heavy catalytically cracked components. The second eight-fuel matrix, designated as the “B” matrix, considered 50% distillation (T50) effects as a function of light paraffinic hydrocarbons (isomerate and light alkylate). The second matrix also considered the effects of heavy aromatics versus heavy paraffins. Physical property data for the twenty-six fuels and ten blending components are included.A summary of the fuels speciation methodology is presented. This is the chromatographic analysis method used within the AQIRP to provide individual chemical species. Results from the AQIRP speciation of the eight fuels comprising the “B” matrix are included. A separate paper (3) will present a more detailed discussion of the test method and results of a cooperative study of the methodology.Miscellaneous physical and speciation data from previous Phase I and Phase II program fuels are also presented in an effort to provide complete information on all AQIRP research fuels.