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Evaporative and tailpipe emissions from a 1987 GM Corsica with adaptive learning closed loop control were measured with six fuels and four temperatures. Measured emissions were total (THC) and speciated hydrocarbons, aldehydes, ethanol, MTBE, benzene, 1,3-butadiene, CO, and NOx. Tests were also performed to determine the effect of air conditioning (AC) and oxygen sensor failure. In general, AC reduced Highway Fuel Economy emissions, increased FTP emissions, and reduced fuel economy for both test cycles. Oxygen sensor malfunction increased tailpipe emissions and fuel economy. Higher levels of regulated tailpipe emissions were generally produced at the low test temperature. None of the fuels tested appeared to offer a consistent reduction in tailpipe THC and CO emissions under the conditions tested.

In response to more stringent emission requirements, catalysts for reducing NO to molecular nitrogen were developed. One of the most promising of these, the three-way catalyst, has been the subject of an EPA study to determine if it produces new tailpipe contaminants. This study and its results are described.