BMW AG has lost the core development team of its i3 and i8 electric vehicle line to Future Mobility Corp, a Chinese startup backed by Tencent Holdings. Carsten Breitfeld, a 20-year BMW veteran who developed the company’s i8 plug-in hybrid sports car, left the Munich-based car maker last month to become chief executive of the Chinese electric car company. The Wall Street Journal reports that three key executives from the “BMW i” electric car group are following him. The defections come as BMW and other premium brand manufacturers are struggling with weak sales of their electric vehicles and a growing threat from new rivals in the nascent electric car market.