If your primary concern is environmentalist you will want to compare your EV to gasoline in terms of relative CO2 production.
When you burn one gallon of pure gasoline you get 19.64 pounds of carbon dioxide (CO2) (from E10, gas containing 10% ethanol, you get 18.95 pounds of CO2).
If you go to https://oaspub.epa.gov/powpro/ept_pack.charts
you can get a figure for how clean or otherwise your electricity generation is by entering your zip code and electricity supplier.
In my area of CT using UI for electricity the CO2 emission rate is given as 571 pounds of CO2 per MWh or 0.571 lbs/Kwh (a relatively clean state). Thus for the equivalent CO2 as produced by burning one gallon of pure gasoline I'll get 19.64/0.571 = 34.4 KWh (for E10 its 33.2 KWh).
Multiplying this value by my charger efficiency, I’ll use 87.8 % as my L2 charger efficiency ( https://www.veic.org/docs/Transportatio ... Report.pdf
). Thus for the same quantity of CO2 released by burning one gallon of gas I’ll get 30.2 KWh in my battery. Since my current average is 4.1miles/KWh (it’s started going up with the warmer weather) I get a pollution mpge of 124.
Efficiency losses during electricity distribution via the grid would already have been taken into account if the government published figure for CO2 lbs/Kwh is based upon what the customer receives, which seems logical. However, there are additional losses incurred with gasoline that I have ignored, so gasoline is in actuality dirtier than the 19-20 lbs of CO2 you get per gallon by simply burning it, because it takes significant energy to refine and distribute the gasoline… and I’ve ignored this. My ultimate aim would be to use home solar power for my electricity source then I’d generate no net CO2 from driving. Unfortunately I live in a very shady area so I’m not the best candidate for this (I don’t want to cut down multiple large trees to go solar).