Over two decades in a little-known, freezing city in northern China, a Swedish man has built a career and witnessed the booming development of the country’s carmaking industry. Gustav Holmgren, 44, whose Chinese name is Ge Siwen, is the legal representative and site manager of ATM (Hulun Buir) Proving Ground Service, which provides cold-weather vehicle testing for carmakers. He is, perhaps, the only foreigner in the city. His company is located in Yakeshi, a small city with a population of...