Tailpipe Rule - GlobalWarming.org

Federal Register / Vol. 75, No. 88 / Friday, May 7, 2010 / Rules and Regulations
25357
The specific form and stringency for
each fleet (passenger car and light
trucks) and model year are defined
through specific values for the four
coefficients shown above.
EPA proposed the equivalent equation
below for assigning CO 2 targets to an
individual vehicle’s footprint value.
Although the general model of the
equation is the same for each vehicle
category and each year, the parameters
of the equation differ for cars and trucks
and for each model year. Described
mathematically, EPA’s proposed
piecewise linear function was as
follows:
Target = a, if x ≤ l
Target = cx + d, if l < x ≤ h
Target = b, if x > h
In the constrained linear form similar in
form to the fuel economy equation
above, this equation takes the simplified
form:
Target = MIN [ MAX (c * x + d, a), b]
Where
Target = the CO 2 target value for a given
footprint (in g/mi)
a = the minimum target value (in g/mi CO 2) 62
62 These a, b, d coefficients differ from the a, b,
d coefficients in the constrained linear fuel
b = the maximum target value (in g/mi CO 2)
c = the slope of the linear function (in g/mi
per sq ft CO 2)
d = is the intercept or zero-offset for the line
(in g/mi CO 2)
x = footprint of the vehicle model (in square
feet, rounded to the nearest tenth)
l & h are the lower and higher footprint limits
or constraints or (‘‘kinks’’) or the
boundary between the flat regions and
the intermediate sloped line (in sq ft)
Graphically, piecewise linear form,
like the constrained linear form, appears
as shown in Figure II.C–2.
economy equation primarily by a factor of 8887
(plus an additive factor for air conditioning).
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