Gasoline is a fuel made from crude oil and other petroleum liquids. Gasoline is mainly used in vehicle engines. Petroleum refineries and blending facilities produce finished motor gasoline for retail sale at gasoline fueling stations.
Petroleum refineries mostly produce gasoline blending components called gasoline blendstocks, which require blending with other liquids to make finished motor gasoline. Most finished motor gasoline is produced at blending terminals, where gasoline blendstocks, finished gasoline, and fuel ethanol are blended to produce finished motor gasoline in different grades and formulations. Some companies also have detergents and other additives blended with their gasoline before delivery to their retail outlets. Blending terminals are more numerous and widely dispersed than petroleum refineries, and they have equipment for filling tanker trucks that transport finished motor gasoline to retail outlets.
Most of the finished motor gasoline now sold in the United States contains about 10% fuel ethanol by volume. Ethanol is added to gasoline partly to reduce greenhouse gas emissions and the amount of oil that the United States imports from other countries.
Gasoline Varies by Grade
Three main grades of gasoline are sold at retail gasoline refueling stations:
Some companies have different names for these grades of gasoline, such as regular, unleaded, mid-grade, medium, super, premium, or super premium, but they all indicate the octane rating, which is the antiknock property of gasoline. (No grade of motor gasoline now sold in the U.S. contains lead.) The lowest octane rating gasoline is usually the least expensive. Vehicle manufacturers recommend the grade of gasoline for use in each model of their vehicles.
The characteristics of gasoline depend on the type of crude oil used to produce it and the setup of the refinery that produces it. Gasoline characteristics are also affected by other ingredients that may be included in the blend, such as ethanol.
Gasoline Changes With the Seasons
The main difference between winter- and summer-grade gasoline is vapor pressure. Gasoline vapor pressure is important for an automobile engine to work properly. During winter months, vapor pressure must be high enough for the engine to start easily. In the summer, a lower vapor pressure is required in many areas to reduce air pollution.
Gasoline evaporates more easily in warm weather, releasing more volatile organic compounds that contribute to health problems and to ground-level ozone and smog. To cut down on pollution, the U.S. Environmental Protection Agency requires petroleum refiners to reduce the vapor pressure of gasoline during the summer.
Gasoline is the Main U.S. Transportation Fuel
In 2021, Americans used about 135 billion gallons of gasoline, including 134.83 billion gallons of finished motor gasoline—or about 369 million gallons per day—and about 0.18 billion gallons of finished aviation gasoline. Motor gasoline is one of the major fuels consumed in the United States and is the main product that U.S. oil refineries produce. Most of the finished motor gasoline sold for use in vehicles in the United States is about 10% fuel ethanol by volume.
U.S. consumers use gasoline in/for:
- Cars, sport utility vehicles, light trucks, and motorcycles
- Recreational vehicles and boats
- Small aircraft
- Equipment and tools used in construction, farming, forestry, and landscaping
- Electricity generators for portable and emergency power supply
Total gasoline consumption (based on energy content) accounts for about 58% of transportation sector total energy consumption and 16% of U.S. total energy consumption, and (based on volume) 45% of total petroleum consumption.
Light-duty vehicles (cars, sport utility vehicles, and small trucks) account for about 91% of all gasoline consumption in the United States.
The amount of total gasoline use various among the states, but Texas and California together account for about one-fifth of U.S. total gasoline consumption.
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