China's auto sales will grow 13 to 15 percent each year over the next 15 years, predicts a think tank affiliated with the central Chinese government.

"The car ownership rate will reach 25 units (per 1,000 people) by the end of this year", said Xu Changming, a senior analyst with the State Economic Information Center, at an auto industry forum held in the north China city of Tianjin this weekend.

In other countries, once the car ownership rate topped 20 units per 1,000 citizens, sales remain strong for another 10 years or so until the ownership rate reaches 100 units, he added. 

"It took Japan eight years and South Korea 12 years (to increase the car ownership rate) to 100 units from 20 units," Xu said. 

Given its wide regional income disparities, Xu predicted it will more time – perhaps 15 years or so – for China to complete the process. Xu cautioned that his forecast did not consider possible government incentives for auto sales. 

"If we continue to stimulate the market as we did last year, it will take China even fewer years than Japan (to increase the car ownership rate to 100 units)," he predicted.

In early 2009, China halved the purchase tax for vehicles with engine displacements of 1.6 liters and below to 5 percent. That year, auto sales soared 46 percent to 13.6 million units.

This year, the China market's rate of growth began to slow in April. In 2010, industry sales are expected to increase 17 percent to 16 million units, according to a forecast made by China Association of Automobile Manufacturers.