For a number of years there has been an ever-growing.
body of governmental regulations to address concerns about.
the environment and energy security. Many of these regulations.
have been aimed at minimizing the environmental.
impact of the automobile. Most regulations have focused on.
the automobile and have resulted in automotive technology.
which significantly reduces vehicle emissions compared to.
pre-control levels. In fact, compared to pre-control era automobiles,.
carbon monoxide (CO) and hydrocarbon (HC) tailpipe.
emissions have been reduced by 96%, while emissions of.
oxides of nitrogen (NOx) have been reduced by 76%.
With this type of progress already achieved via automotive.
technology, it was apparent that if further gains were to be.
made, it would be necessary to focus on cleaning up the fuels.
that these vehicles use.
Of course, compositional change to gasoline is not.
something new. Refiners have, over the years, altered the.
composition of gasoline in response to technological advancements.
and changes in demand for end use products.
However recent compositional changes have been, and will.
continue to be, driven by environmental considerations.
The first such change was the wide-scale introduction of.
unleaded gasoline in the early 1970s followed by the phasedown.
of lead levels in leaded gasoline (1975-1985). This was.
followed by Phase I of the U.S. Environmental Protection.
Agency's (EPA) fuel volatility regulations (1989). Further.
reductions in fuel volatility were achieved in 1992 under.
Phase II of these regulations. These programs have all.
resulted in compositional changes to gasoline.
In the late 1980s several areas of the U.S. implemented.
oxygenated fuel mandates to reduce CO emissions. Such.
areas included various cities and towns in Colorado, Nevada,.
Arizona, New Mexico, and Texas. These programs required.
the sale of oxygenated fuels in certain winter months. Oxygenated.
fuels contain ethanol, methyl tertiary butyl ether.
