Here's a quick version for my local rates.

An EV will use about 300Wh of electricity per mile. This varies a bit depending on the car (a massive Model S will use more than a Leaf) and how you drive it, but it's a decent approximation. I pay about 13 cents/kWh. That makes my energy cost for driving an EV about 3.9 cents/mile. I believe that's 300Wh out of the battery, so you probably want to add another 10% or so for charging inefficiency, but I'm not sure exactly what the numbers are there so I'll leave them be.

My last car got 40MPG. At current local gas costs of $2.50/gallon, that's 6.25 cents/mile.

And of course, a lot of people think that current gas prices are anomalously low and won't last.