Do you think electric cars being mainstream will improve global warming ?

Electric cars make up a tiny portion of the automotive fleet even in rich countries like America. Around the world in places where the infrastructure isn't so built up, it may be decades before electric cars become even a blip on the radar.

Also, while cars and such certainly contribute to the climate change problem, the major contributors are more likely industrial polluters and such. Until those sources are addressed, I don't think the car thing is going to make much of a dent.