Shanghai - China has overtaken the U.S. as the world's biggest market for automobiles, the first time any other country has bought more vehicles than the nation that produced Henry Ford, the Cadillac and the minivan.

Now that the Chinese buy more cars and trucks than Americans, the shift could produce ripples for the environment, gas prices and even the kinds of cars automakers design.

More than 12.7 million cars and trucks will be sold in China this year, up 44 percent from the previous year and surpassing the 10.3 million forecast in the U.S., according to J.D. Power and Associates.

China has long been expected to overtake the U.S. since its population of 1.3 billion is more than quadruple that of the United States. But the increase in sales happened much faster than anyone expected because of China's tax cuts, its stimulus program and a depressed American market.

Two years ago, J.D. Power predicted China would pass the U.S. in 2025. Earlier this year, it forecast 2009 sales of just 9 million vehicles for China.

After a sharp slowdown in auto sales late last year, the Chinese government cut taxes on small cars and spent $730 million on subsidies to encourage sales of SUVs, pickups and minivans. A big stimulus program also boosted truck sales by pumping money into construction.

Auto sales were expected to rise with China's stimulus, but they have far exceeded expectations, said Jeff Schuster, J.D. Power's executive director of automotive forecasting.

Most experts think the top-sales title will shift back and forth between China and the United States for the next several years, with China ultimately prevailing.

Improving sales of autos and other big-ticket items is key to Beijing's strategy to promote stronger domestic consumption and lower dependence on exports.