I prepared two scenarios to estimate the future number of electric vehicles (EV), and total number of cars, on a global scale.
The first scenario is a business as usual (BaU) scenario, where the annual number of new cars is based on the average growth rate of total cars from 1999-2016 (calculated to be 3.28% - data from OICA). The annual number of new EV and the total stock of EV were estimated in line with the target of 41 million cars sold by 2040 (What will the global EV Light-Duty Vehicle fleet look like through 2050?, Sitty & Taft, Fuel Freedom Foundation, 2016).
The second scenario is called 2DS, as it is in line with the 2 degree Celsius scenario from the International Energy Agency (IEA). This corresponds to reaching 80% greenhouse gas emission reduction by 2050. In this scenario the annual number of new cars is based on the low growth scenario in Sitty & Taft (2016), which leads to 2% growth until 2040, and 1% until 2050. The annual number of new EV and the total stock of EV were based on the IEA goals of 25 million stock by 2020 and 200 million stock by 2030 (Global EV Outlook 2017, IEA, 2016).
For both scenarios, the total stock of cars is based on OICA figures including the current stock in use (2015), the average of retired vehicles (2006-2015), and the annual number of cars. The ratio of battery electric vehicles (BEV) to plug-in hybrid electric vehicles (PHEV) was based on the average of annual new BEV/PHEV registrations (data taken from the IEA, 2008-2016). This lead to an increase of BEV over PHEV, with 100% BEV reached by 2028.
