According to Reuters Beijing, China car sales in the first half of 2006 climbed almost 50 percent year on year, with General Motors staying out front.   China saw sales of 1.804 million cars in the domestic market in the first half, up 46.9 percent year-on-year, Xinhua news agency said, quoting the China Association of Automobile Manufacturers.   The top ten companies are, in descending order: Shanghai GM, Shanghai Volkswagen, FAW Volkswagen, Chery, Beijing Hyundai, FAW Toyota, Tianjin-FAW Xiali, Geely, Guangzhou Honda and Dongfeng Peugeot Citroen.   GM, which overtook Germany's Volkswagen AG last year to become China's biggest vehicle seller, sold 453,832 units in the six months ended June, up 47 percent from a year earlier, the company said last week. Statistics show that the ten companies maintained steady growth in the first half year with sales surpassing 100,000 and ranging from 183,900 to 100,200.