Contents I. Introduction
As the most common means of transportation, petrol-based vehicles bring great benefits to human societies. This, however, comes at the price in terms of environmental degradation and health hazards. In the United States, greenhouse gas (GHG) emissions from the traditional transportation sector accounted for about 24.9% in 1990 and 28.2% in 2012, and accounted for the largest share of growth in total emissions (103%) between 1990 and 2012 [3]. In other countries, like China, GHG emissions from the transportation sector are even more significant. This reinforces the interest in electric vehicles (EVs) [21], [38]. It has hence been projected that replacing traditional motor vehicles by electric ones can reduce GHG emissions by up to 60% [36]. Despite the obvious gains from this change in technology, the path leading to a widespread adoption of EVs remains clouded with obstacles. One of the key factors preventing an immediate main streaming of this technology is a simple economic one: consumers are reluctant to bear the cost of switching. But from a governmental perspective, it is a cost-efficient decision to upgrade public transit systems as it contributes to reducing pollution and increasing social welfare [21], [38]. Consider Beijing, for instance, the most well-known Chinese city suffering from air pollution where taxis account for about 4% of the total vehicles, but results in about 25%–30% of traffic flows [30]. Projecting these numbers to a national (Chinese) level, a reduction of GHG emissions could be reduced by 18% by upgrading only 4% of the vehicles [6]. Naturally, transportation measures affecting GHG emissions such as carpooling services [44], [45] and other cruising miles reduction schemes [42] have been proposed in the literature. However, given the magnitude of the current air quality crisis in China, it would be unsurprising that policy makers are considering upgrading their taxi fleet to EVs - actually pilot schemes have already been implemented in cities such as Hangzhou and Shenzhen [21], and Beijing has already decided to upgrading its entire taxi fleet to EVs within four years [8] .
