Raúl Bajo and Miguel Ángel Borrella, researchers at the Navarra Center for International Development, have studied whether the impact of VTCs in Spain has boosted the purchase of less polluting cars by traditional taxi drivers. The aim of the research is to observe whether increased competition in the sector helps to renew the taxi guilds' cars in line with the European Union's environmental requirements. 

The result of the research was that the interest of the taxi trade in buying new environmentally friendly vehicles has increased by 30%. It has been found that this dynamic has occurred in metropolitan areas where VTCs are present and that the opposite is true in places where competition has not yet arrived. 

More information about this research can be found in this interesting article in El Mundo with statements by Bajo and Borrella.