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

Transportations Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
greater proportional impact than those focused on light-duty vehicles because of the
higher tax rate on diesel fuel (24.4 vs. 18.4 cents per gallon). A shift from gasoline to diesel
light-duty vehicles would have a smaller revenue impact, since while less total fuel is
consumed, the tax rate on diesel fuel is higher.
This analysis describes potential impacts to Federal transportation revenues under the
current finance scenario. Funding shortfalls could be mitigated or avoided in the future
through shifts in tax structures or through alternative infrastructure funding mechanisms.
� 3.2 On-Road Light-Duty Vehicles
Light-duty vehicles (LDV) include passenger cars, light trucks, minivans, and sport-utility
vehicles (SUV). 7 These vehicles are primarily used for personal transportation, although
some are placed in service for commercial purposes. Light-duty vehicles are the single
largest GHG-emitting subset of the transportation sector, accounting for over half of U.S.
transportation greenhouse gas emissions—57 percent, or 1,232 mmt CO2e in 2006. Future
efficiency improvements established under the 2007 EISA are expected to reduce their
contribution somewhat, to 1,081 mmt CO2e or 50 percent of all transportation emissions in
2030. However, light-duty vehicles still represent the single-largest opportunity for
reducing GHG emissions from the transportation sector.
Strategies for improving the efficiency and reducing GHG emissions from light-duty
vehicles discussed in this section include:
• Advanced conventional gasoline vehicles, which utilize improvements to the gasoline
internal combustion (IC) engine along with drivetrain and other vehicle attributes
(such as wind resistance and weight) to improve fuel efficiency;
• Enhanced diesel vehicles that can meet stringent new emissions standards while
providing the efficiency and GHG benefits of diesel engines;
• Hybrid-electric vehicles (HEV) that combine the internal combustion (IC) engine of a
standard vehicle with the motor and battery technology of an electric vehicle; and
• Plug-in hybrid electric vehicles (PHEVs), which are similar to HEVs but have more
batteries and can plug into the local power grid, beginning each trip on battery power.
Fuel-cell and battery electric vehicles also offer the potential for significant long-term
gains in light-duty vehicles energy efficiency. These technologies rely on fundamentally
which is consistent with AEO Reference case projections of relatively constant fuel consumption
(with increases in VMT offsetting increases in fuel efficiency).
7 Trucks and larger vans are classified as light-duty if they have a gross vehicle weight rating (i.e.,
total load carrying capacity) of less than 8,500 pounds.
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