According to the engine displacement, divided into a miniature (1 liter), light level sedan (1-1.6 liters), intermediate (1.6-2.5 litres), senior sedan (2.5 4 liters), limousine (4 liters). The plan should also be linked to capital management in addition to the analysis of market objectives In 1934, professor rei, of the center for fluid mechanics, used model cars to measure the aerodynamic drag of various bodies in wind tunnels Followed by Edwards and bear published in his 1961 book "the theory of corporate earnings and measurement of the current operating profit is defined as the sales revenue more than the amount of current production and cost of sales, which can realize the cost savings is in this issue of asset price increases, which can realize the history of the cost savings are the pin commodity costs and the difference between the current purchase price; The realized capital gains are the amount of sales revenue greater than the historical cost when dealing with long-term assets. They argue that "these incremental sums provide investors with a reasonable starting point for measuring the scale of relative affluence and a detailed analysis of the company's operating results and comparable financial conditions". They stress that any full income analysis should take into account both realized and unrealized benefits and classify them by source. When are advantageous to occur, such as no record, will not only lead to current income can't reflect, but also can lead to later to sell assets to income and related costs to wrong ratio; Operating earnings and, on the other hand, the production gains is usually produced by different management decisions, and adopted different circulation form, therefore, make the same comment on both, will weaken the role of the income statement.