Environmental Engineering Reference
In-Depth Information
• Need of the nation to conserve energy
The EPA and NHTSA are often at odds with each other over the intent of the CAFE regulations. The EPA en-
courages consumers to purchase more fuel-efficient vehicles, while the NHTSA is concerned that smaller,
more fuel-efficient vehicles may lead to more traffic deaths.
For CAFE purposes, cars and light trucks are considered separate and have different standards. As of 2004,
cars must exceed 27.5 mpg, and light trucks must average 20.7 mpg. The standard for trucks under 8,500
pounds was 22.5 mpg in 2008, 23.1 mpg in 2009, and 23.5 mpg in 2010. Starting in 2011, new standards will
take effect, and the targets will be based on the truck size footprint.
How to Calculate Percent Change
A vehicle's change in weight can be used as an example demonstrating how to calculate percent change.
, where
V
1
is the initial value, and
V
2
is the second value.
If vehicles' average weight went from 3,220 pounds to 4,066 pounds, you would calculate the percent
change as follows:
