The Chinese megacity of Shenzhen has successfully switched 100 percent of its 16,359-vehicle bus fleet to electric vehicles, reaching its goal just six years after it vowed to move away from diesel engines, according to reporting by CleanTechnica and other news outlets. The fleet — which has three times as many buses as New York City — serves a population of 12 million. The switch is expected to save the equivalent of 345,000 tons of diesel fuel and cut 1.35 million tons of carbon dioxide emissions.