As China's ride-hailing market heats up again, Alibaba Group's AutoNavi maps service has found a way to join the fray by launching a ride-hailing booking service. The 700 million users of AutoNavi's map service can now, for the first time, choose from a list of ride-hailing providers, including China's dominant player Didi Chuxing, as well as Ucar Inc and Shouqi Limousine & Chauffeur. To attract users, AutoNavi is offering generous subsidies to encourage ride-...