Yes, so in the more typical 3 gallons of gas car (33.3 mpg) that would set you back $9-$12 you pay half as much for the energy But electricity, like gas prices, varies.

A more interesting way to look at it from my perspective is that each 'mile' has an energy cost of 4.5 cents vs 9 cents. And in a 10,000 mile year that is $450 not spent.

There are still a lot of unknowns in terms to total cost of ownership, battery pack replacement, other maintenance.

edit: $450! Just made it in under the wire. Thanks.