Between 2015 and 2017, the number of NEV brands doubled and the number of NEV models available in the Chinese market tripled. This rapid development of China's new energy automotive industry is one result of the pro-EV policies made at the national and local levels. Because China is now transitioning from pilot- and policy-directed development and a more meaningful engagement with industry, challenges to NEV commercialization consist of mainly local deployment and market protectionism. This study proposed a new index for assessing relative market openness for competitive NEV development: "the NEV Market Openness Index". The index was developed on the basis of conventional diversity combined with penetration indexes, both adopted from biological studies, with a particular focus on passenger NEVs, and based on data from 23 Cities and 20 provinces.