In the American society of automotive engineers standards SAEJ 687 c for automobile is defined as: power driven by itself, with a driving device, can in a fixed orbit outside the road or on regional transport passenger and cargo or vehicle traction vehicles. Cars are divided into bicycles and trains according to the overall structure. Cycling is a basic form. 4 x 2, 6 x 4, 4 x 4 and 6 x 6 are used to represent the driving characteristics. The previous number represents the total number of wheels (double tire and still count a wheel), and the latter number indicates the number of driving wheels. If all wheels are driven wheels are called all-wheel drive vehicles. The train is made up of a tractor or a bicycle trailer or semi-trailer. Car generally can be divided into the following categories, according to the use cars, buses, freight cars (commonly known as the truck), off-road vehicle, traction motor, dump truck, special vehicles, semi-trailer and special semi-trailer. In addition, the national standard has strict regulations on the content of various chemical components of gasoline such as benzene and olefins. Alkenes are high in content, which can produce gelatinous substances in the process, and accumulate in intake manifold and valve catheter. When the engine is in normal working temperature, there is no abnormal phenomenon; When the engine has cooled for some time, the glial will stick the valve inside the valve tube. When you start the engine, you will have a top valve phenomenon. The toxic benzene content should not exceed 1%. The importance of gasoline was not recognized in the 19th century, when it was used in a great deal of kerosene. The oil refining then relied on simple distillation processes to separate the different components of the oil from the boiling point. The boiling point of the kerosene component is higher, and the use of safety when lighting lamps becomes the main product of crude oil refining, while gasoline and other components are often burned as fuel. By the mid - to late 19th century, the successful use of gasoline engines in 1886, in 1886, the gasoline engine was successfully used as a driving force, thus the importance of gasoline increased. But using distillation, only 20% of the gasoline can be extracted from crude oil. In 1911, the standard oil company have solved the problem of low gasoline yield, by William burton and Robert hamm forest thermal cracking process of the invention, the heavy quality heating gas oil cracking of light gasoline fractions, such as to overall improve the gasoline yield, thermal cracking process in 1913 won the patent license in the United States. The subsequent catalytic cracking process has further improved the gasoline yield and octane value. The Resolution Foundation said the loss of pay across all sectors took the average loss for each of the UK’s 800,000 agency workers to £500 a year, up from £430 last year. marque