Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportations Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
provide increased actual or perceived interior volume, while decreasing outside
dimensions, also can result in weight reduction. The final method, shifting market
demand to smaller vehicles, depends largely on changes to consumer demands.
Even after considering the adoption of weight reduction strategies to date, average vehicle
weight in the United States has been increasing at a rate of about 1 percent per year since
the early 1980s (Bandivadekar et al., 2008). This is due in large part to the recent increase
in SUV sales; however, many individual models have increased in size and weight with
each redesign cycle. Adding features for comfort, utility, and safety generally increases
the weight of vehicles, so efforts to decrease weight must overcome these upward trends.
Magnitude and Timing of Emission Reductions
The GHG reduction obtained by replacing a conventional gasoline LDV with an advanced
gasoline LDV depends upon the fuel economy difference between the conventional and
the advanced vehicle, and the miles traveled per year. However, the fuel economy of the
baseline vehicle fleet is dynamic, improving over time in response to market forces such as
higher fuel prices, as well as to mandates such as the revised CAFE standards. For
example, the 2009 AEO projects that in-use vehicle efficiency for LDVs will increase from
21.8 miles per gallon (mpg) in 2010 to 28.2 mpg in 2030. 11 In order to evaluate the benefit
of replacing conventional gasoline vehicles with advanced technology packages,
comparisons are made relative to the baseline (AEO forecast) future year fleet average fuel
economy.
Individual Technology Benefits
While some of the technology options discussed in this section are readily available to the
consumer, others are just entering the marketplace, while still others are in an early
development phase. In general, multiple options are expected to penetrate the market in
varying degrees over time, depending upon regulatory mandates, fuel prices, and
consumer preferences. The AEO Reference case includes a highly detailed breakout of 63
technologies, many of which involve efficiency improvements, providing yearly market
penetration levels reflecting revised CAFE impacts through 2030. 12 This provides a
baseline for which additional improvements can be compared against.
The following analysis provides a brief discussion of some of the more significant
efficiency improvement options and their estimated market penetration potential.
11
As discussed in Appendix A, this forecast accounts for targets for corporate average fuel economy
(CAFE) standards established in 2008 under the 2007 Energy Independence and Security Act, but
not for revised standards considered in 2009 by the Obama Administration.
12
See AEO 2009, Supplemental Table 68. Many of these options involve the same technology
implemented in varying degrees of intensity—for example, Engine Friction Reduction I-IV.
3-27