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The effects of fuel sulfur level on tailpipe emissions from advanced technology vehicles were explored in Phase 1 of a study conducted under the Petroleum Environmental Research Forum. In this study, fuels having three different levels of sulfur were tested according to the Federal Test Procedure (FTP) in low-mileage production vehicles designed primarily to meet California's Transitional Low Emission Vehicle (TLEV) standards. The three fuels consisted of a base gasoline containing 25 ppm by mass of sulfur, with the other two fuels created by doping the base fuel to 300 ppm and 600 ppm sulfur, respectively. Nine TLEVs and one Federal Tier 1 vehicle were tested at least twice on each fuel in an order that was balanced in time and randomized among the vehicles.

Under the auspices of the Coordinating Research Council, a program was conducted to determine the effect of gasoline/oxygenate blends on exhaust emissions (particularly carbon monoxide) for three types of emission control technologies. Tests were performed at sea level and high altitude and at temperatures of 75°F, 50°F, and 35°F. The primary fuel set consisted of a 13 psi RVP hydrocarbon-only gasoline, a hydrocarbon/11 volume percent MTBE blend, and a hydrocarbon/splash-blended 10 volume percent ethanol blend. Additionally, sea level tests were conducted with a hydrocarbon/11 volume percent ethanol matched-volatility blend and at limited conditions with a hydrocarbon/16 volume percent MTBE blend. The cars and emission control technologies tested were six 1986-88 “Adaptive Learning” closed-loop three-way catalyst systems, six 1983-86 closed-loop three-way systems without the adaptive learning capability, and four 1979-80 carbureted oxidation catalyst systems.