Not alone do we already have too many cars, some predict we may go from 1.4 billion to 2.5 billion in the next 20-30 years. So, we'll have lots of electric cars and lots of petrol and diesel cars.
We are breaching multiple boundaries for a safe environment. We must address the problem of overconsumption and its impacts on soil, air and water. Focusing on just one metric such as CO2 will do greater total damage. We must have a basket of metrics covering air, water and soil.