LONDON: Global electric vehicle sales grew 21 percent year-on-year in July, the slowest rate since January and down from 25 percent in June, as momentum in plug-in hybrid sales in China slackened, market research firm Rho Motion said on Wednesday. China is the world’s biggest car market and accounts for more than half of global EV sales, which in Rho Motion’s data include battery-electric vehicles and plug-in hybrids. Its overall car sales growth slowed in July, with BYD , the world’s largest EV maker, recording its third monthly drop in registrations.