HANGZHOU, China -- When a wealthy street-car racer knocked down and killed a young man from modest origins last May, it ignited the flames of class conflict in this prosperous city in eastern China.

The 20-year-old driver, Hu Bin, grew up the pampered son of a merchant family rich enough to own multiple cars and apartments along Hangzhou's tree-lined boulevards. The victim, Tan Zhuo, a 25-year-old telecom engineer, came from a gritty rural town where his laid-off parents struggled to pay tuition to fulfill their son's dream...