The average rate in the U.S. is $0.132 per kWh (September 2017), which is the cost we use in the chart below
The charts are for $0.1287 per kWh and Gas @$2.73.2
https://www.clippercreek.com/cost-charge-electric-vehicle/
Many calculators available where you can plug in your own numbers.
This chart lists all the EVs.
Wow, those are significant savings - up to 70% for the Leafs and the Tesla. In Canada it would be even larger considering how much more our gas costs.
I guess the next thing to look at is the capital costs. Cost of electric vs closest gas cousin, resale values, ect….