Environmental Engineering Reference
In-Depth Information
Technical Note . : CAFE Standards
The CAFE standard is about the gasoline consumption of a
fleet of different vehicles. It is not the average mpg of the
fleet, but is related to the amount of fuel required to move
the entire
fleet by a given distance. It is easier to use an
example than to give the equations which won
'
t mean much
to most people. Suppose you have a two-car
fleet. One of
them gets
mpg while the other gets
mpg. If you drove
both for one mile the
mpg vehicle would use a tenth of a
gallon of gas while the
mpg vehicle would use one-
hundredth of a gallon. The total for the
miles is
.
gallon
so this two-car
fleet has a CAFE average of
divided by
.
,
or
mpg. If my
eet has two
mpg vehicles and three
mpg vehicles, the total fuel used in moving all of them
one mile would be
.
gallons. Five total miles moved
divided by
.
gallons of fuel used is about
mpg. I can
use the same method if I have
different models in a
corporate
fleet with different numbers of each model on
the road. It is even more complicated when different types
of vehicles are held to different standards. That was the case
before the new standards and is still the case, though today
the different requirements are based on size rather than
weight as they were before. For more details see the website
of
c Safety Administration
( http://www.nhtsa.dot.gov/ ) and go to their section on fuel
economy.
the National Highway Traf
will easily be met. Europe is already much better
than the United States. There are opportunities in
advanced conventional hybrids, diesel engines, and new
style gasoline engines.
The PHEVs are likely to be revolutionary, and just how
revolutionary will depend on the development of more
Search WWH ::




Custom Search