Oil derivatives are the dominant source of fuel for transportation systems. You have probably seen news coverage of “hydrogen” and “electric” powered vehicles, but these sources are still very much in their infancy. Gasoline is the primary fuel source for cars, trucks, and other passenger vehicles, but regular gasoline systems are not the only systems available. Diesel systems are the preferred types for commercial vehicles, cargo ships, and trains. http://www.yey-business.com/diesel-engine/diesel-engine-accessories/