In the early 20th century, famous American economist elvin fisher developed the theory of economic gain. In its book "the nature of capital and yield", first, the concept of yield is analyzed in terms of the performance of earnings, and three different types of benefits are proposed: But even at its lowest point, interest rates were just 0.18 percentage points higher, not a quarter-point rise in interest rates. Like most of the developed countries, France's car market also belongs to the mature market, tend to be saturated, most new car sales are no longer a first-time buyers of consumer is bought, is more of a used car. Subject to regional economy, the cost of living, and the influence of cultural background, etc, the French are more keen to sta domestic car, in French, so we will find that their vehicle seems to is not match with the national economic development level, and it is precisely the characteristics of these European developed countries have in common, they did not imagine the high to the requirement of cars, more practical. Psa Peugeot Citroen sold 51,188 cars in France in 2014, down 2.2% from a year earlier, according to data from the auto industry. Sales at Renault also fell 0.4 per cent year on year to 37,898 units. In addition, Volkswagen, ford, Toyota and most other car companies suffered declines in France in 2014, and France's current car market is not expected to sell well.