> 80% of the solution
In the US, only 39% of emissions are from fossil fuels used for transportation [1]. Where I am, around 60% of my EV power comes from natural gas plants that run at night, where electricity is 3.5x cheaper (electricity costs more than gas during peak hours where I am).
With the lack of new nuclear, and the required 25-50% increase in our power grid, a quick (as in 20 year) change in EV adoption would almost certainly mean that more of these natural plants come online when charging happens, negating at least some of the CO2 savings.
80% seems fictitious.
[1] https://www.eia.gov/tools/faqs/faq.php?id=307&t=10#:~:text=C....
