Here's some easier math... Assume I have a fully depleted battery which requires 15kwh to fill. My electric rate is $0.088 / kwh = $1.32. Gasoline where I live is about $2.50/gallon. If you assume that I get approximately the same EV range per charge as I get on a gallon of gas - ~45 miles, then: $2.50-$1.32 = $1.18 difference on each full charge, in MY situation, assuming that I only charge at home; but, I charge (120-volt, 16-amp) at one of my work places at no cost.