One outcome of China’s expected entry into the World Trade Organization is likely to be a dramatic rise in car ownership among the nation’s 1.3 billion citizens, a possibility that alarms some American enviros who worry about increased pollution and emissions of greenhouse gases. Under the WTO, China’s import tariffs on cars will drop to 25 percent, from current levels of at least 80 percent, and foreign automakers will be permitted to make consumer car loans, which are presently unknown in China. “We are starting a trend, common in Western countries, for rich people to move out of downtown, buy a car, and move to the suburbs,” said Zang Xinmin, a high-ranking Shanghai official. “In the future, it will be common for people to drive 60 miles to work, just like in California.”