An Endangered Panda: The largest foreign-owned enterprise ever approved in China, a billion-dollar venture to build cars, may become the nation's biggest investment flop. Panda Motors, a company with close links to the Korean Unification Church of the Rev. Sun Myung Moon, was to be operating this year, with a goal of assembling 300,000 cars annually for export by the mid-1990s. But the showpiece project has run into the bureaucracy. Panda said it would build all its cars for export. But the government's China National Automotive Corp. believes it was trying to enter the domestic market through the back door. Calling Panda a threat to the domestic car industry, it has fought the company to the point that Panda is now seeking an equity partner in the venture.