General Motors (GM) and Chinese partners plan to spend more than $1 billion on a new car plant in Chongqing, a major manufacturing hub in Southwest China, to keep up with demand in the world's largest auto market. SAIC-GM-Wuling -- the U.S. auto giant's joint venture with Chinese firms SAIC and Wuling Motors -- will begin construction early next year on the 6.6 billion yuan plant, which is expected to open in 2015. It will have an annual production