(MTBE) or other oxygen-bearing compounds. Oxygenates.
chemically enlean the air/fuel mixture resulting in more complete.
combustion and lower CO emissions.
In 1990, Congress passed, and the President signed,.
the 1990 Clean Air Act Amendments. These amendments.
represent the most comprehensive clean air legislation in.
history. Title II of these amendments required further environmentally.
driven changes in gasoline.
In the fall of 1992, over thirty-five areas of the nation.
failing to meet the federal standard for CO were required to.
implement oxygenated fuel programs similar to those in the.
areas mentioned above.
There were also requirements addressing ozone nonattainment.
that took effect in 1995. These regulations required.
the introduction of "reformulated gasoline" in the nine.
worst ozone non-attainment areas. The regulations also.
contained provisions for other ozone non-attainment areas to.
"opt in" to the program.
Clearly the addition of oxygenates and reformulation of.
gasoline have led to further compositional changes in gasoline.
Each compositional change in gasoline, whether driven.
by efforts to increase production, improve octane quality, or.
improve the environment, has advantages and disadvantages.
at the refinery as well as in the automobile.
While these regulations set specifications to control the.
environmental impact of gasoline, there are also specifications.
and guidelines to control the performance characteristics.
of gasoline to ensure that it performs satisfactorily. Such.
guidelines are usually based upon American Society for.
Testing & Materials (ASTM) standards. As more and more.
changes occur in the composition of gasoline, it becomes.
increasingly difficult to balance environmental specifications.
against performance based specifications and guidelines.
A former General Motors executive, Alfred P. Sloan,.
recognized that, for automotive scientists and engineers "The.
central problem has been to develop a more satisfactory.