The transportation sector is by far the largest user of petroleum-based products (excluding the non-petroleum content of liquids) in the United States. In 2009, transportation accounted for 72 percent of total U.S. petroleum demand, consuming 12.9 million barrels per day (MMbbl/d) of petroleum out of a national total of 18.0 MMbbl/d. The Annual Energy Outlook 2011 Reference case, which reflects a scenario in which current laws and regulations remain unchanged, projects that transportation will continue to dominate petroleum consumption, with demand growing to 13.7 MMbbl/d out of a U.S. total of 18.9 MMbbl/d by 2035.

Light-duty vehicles (LDVs) consume the largest portion of petroleum products in the transportation sector, accounting for 8.2 MMbbl/d in 2009. Projected LDV petroleum consumption in the AEO 2011 Reference case is still around 8.2 MMbbl/d in 2035. Personal travel demand rises across the projection period, driven by increasing disposable personal income; however, a 34-percent increase in the fuel economy of the LDV fleet and the use of 1.8 MMbbl/d of ethanol offset petroleum product consumption, reducing the LDV share of transportation demand and total U.S. petroleum demand to 60 percent and 43 percent, respectively. Increases in fuel economy standards beyond those already set for LDVs through 2016 or mandated by law through 2020 are not considered in the Reference case projection. If established, further fuel economy standards could substantially reduce the long-run projection for LDV petroleum use.

Heavy-duty vehicles (HDVs) consume the second-largest portion of petroleum products in the transportation sector, accounting for 2.1 MMbbl/d and representing 17 percent of transportation demand and 12 percent of total U.S. petroleum demand in 2009. HDVs represent the largest area of growth in transportation petroleum consumption, growing from 2.1 MMbbl/d to 2.6 MMbbl/d, driven by an over 50-percent increase in the value of industrial output, with HDVs affected primarily by growth in the movement of high-value goods that are carried by freight trucks, which is partially offset by only a small improvement in HDV fuel economy. The Reference case projections for HDV fuel use outlined above do not reflect possible fuel economy standards for HDVs that are currently under consideration, and would likely change if binding standards were to be established.

Aircraft also represents a growing area of petroleum demand, increasing from 1.3 MMbbl/d in 2009 to 1.5 MMbbl/d in 2035, driven by the impact of rising income on personal travel and growing air freight demand for export, tempered by an increase in aircraft fuel efficiency and rising aircraft load factors. Petroleum product demand for the marine and rail transportation grows slightly, reaching 0.6 MMbbl/d and 0.3 MMbbl/d, respectively, in 2035. Marine and rail petroleum product demand grows as a result of higher industrial output due to the increased movement of bulk commodities such as corn and coal.

1In the context of this discussion, petroleum-based products exclude the ethanol used with various gasoline blends or the synthetically produced liquids from coal, natural gas, and biomass.
2Light-duty vehicles include passenger cars, light-duty trucks, and light-duty commercial trucks of 8,500 to 10,000 pounds gross vehicle weight rating.
3 Ethanol includes both E85 and ethanol blended into motor gasoline up to E15. E85 refers to a blend of 85 percent ethanol and 15 percent motor gasoline. To address cold starting issues, the percentage of ethanol varies seasonally; the Annual Energy Outlook 2011 uses an annual average ethanol content of 74 percent. E15 refers to ethanol blended into motor gasoline up to a 15 percent content.
4Heavy-duty vehicles include trucks with a gross vehicle weight rating of 10,001 pounds and above as well as intercity, school, and transit buses.
5Load factor represents the fractional amount of seats filled on a given aircraft.