There is positive externality to society when you avoid using such a high polluting car.
Submitted by Ko from India on 29/09/2017
From our crowdsourced Open Dictionary
2
economicsa side effect or consequence of an industrial or commercial activity that affects other parties without this being reflected in the cost of the goods or services involved, such as the pollination of surrounding crops by bees kept for honey
The first is to address negative externalities that aren't reflected in market prices.