A gallon of gasoline emits about 11.8 kg of CO2 if you include refining. https://innovationorigins.com/en/producing-gasoline-and-dies...
One kilowatt-hour of electricity currently emits about 372grams of CO2, a number that has dropped from 500 grams in 2012.
A new Chevy Malibu gets 32.5mpg combined. Hummer EV gets 47mpge combined, or about 1.394 miles per kWh.
363gCO2 per mile for the Malibu, 267gCO2/mile for the Hummer.
I don’t think using hyper-specific region specific metrics makes a lot of sense considering the grid is all connected. (At least, the East Coast and Midwest, Texas doing its own thing, and then the west Coast.) in any case, the grid is getting lower emissions over time and could go MUCH lower than current (maybe half or less) over the full life of any new vehicle.
Also, a Hummer EV is displacing other large vehicles. And if everybody drove subcompacts or other hyper efficient gasoline cars then we’d have less of a problem anyway. But not everyone is doing that. And a lot of people don’t want to. From a political economy standpoint then this is still a huge net win. Every new car and truck needs to at least have a plug in it within the next 5 to 10 years, and then we can start penalizing larger and heavier vehicles more directly.
EDIT: what we should do is expand the EV tax credit. GM no longer qualifies as they used theirs up, like Tesla. Mostly just foreign EV makers qualify, which cannot be the real intention of lawmakers when they made the law.
We can use the EV credit as a tool for improving efficiency. Instead of subsidizing per kWh of battery, we subsidize per mile of range. The first 50 miles of range (ie to be a plug in hybrid, but need at least 6.6kW charging speed) are incentivized at $100/mile of range. The next 200 miles of range $25/mile (under the condition of 100kW fast charging capability).
That way car companies are incentivized (even more) to maximize miles per kWh. Small, hyper-efficient EVs will be disproportionately credited. For a given kWh of battery, you’ll make more EV credit money as a carmaker putting it in a small, very efficient car than a big Hummer. But unless we renew the EV credit (and make it per kWh), there isn’t this (additional) incentive.