commercial, and economic considerations that determine the types of vehicles selected and how they are used; and by the performance of the infrastructure itself (e.g., in managing congestion). Energy use in air transportation, for example, is influenced by air-traffic management, and energy use in freight transport is affected by the possibilities (or lack thereof) for intermodal transfers. The functioning of the underlying physical and economic systems, in other words, can foster—or in some cases hinder—energy efficiency.

Potential for Energy Efficiency Improvements in Passenger Transportation

Automobiles account for the vast majority of local and medium-distance passenger-trips17 (those under 800 miles); airlines dominate for longer trips.

Light-Duty Vehicles

Globally, the major motivators for energy efficiency in light-duty vehicles (LDVs) are fuel prices, vehicle fuel-economy regulation, personal preferences, and environmental concerns. In Europe, a long history of elevated fuel taxes has been a major reason that motorists there have put a high priority on fuel efficiency when purchasing automobiles. In the United States, the corporate average fuel-economy (CAFE) standards have been the main impetus for boosting vehicle efficiency. Falling real fuel prices from 1980 to 2005, however, encouraged consumers to purchase larger, more powerful, and heavier vehicles rather than to seek greater fuel economy. However, during periods of high fuel prices (such as those prevailing in mid-2008), U.S. consumers have demonstrated more interest in fuel economy.

Today, the average fuel economy of new vehicles sold in the United States is about 25 mpg (new cars average 27.5 mpg compared with 22.3 mpg for light trucks). The U.S. Energy Independence and Security Act of 2007 (EISA 2007; P.L. 110-140) requires that CAFE standards be set for LDVs for model years 2011 through 2020. This provision aims to ensure that, by 2020, the industry-wide CAFE for all new passenger cars and light trucks combined will be at least 35 mpg18—a 40 percent increase over today’s average of 25 mpg.

While fuel economy in the United States has not improved for almost 30


One passenger taking one trip, regardless of trip length, is referred to as a passenger-trip.


The Obama administration has recently proposed that these requirements, specified by Subtitle A of EISA 2007 (P.L. 110-140), be accelerated.

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