I just barely stay under my tier 1 usage that is charged at $0.14707 KWH. If I get an electric car it will be at tier 2 rate of $0.17028 KWH. I don’t know what the rates are at tier 3 & 4. Seems like they always figure the electric car at the low tier 1 rates.
My electric comes in at about $0.16 per kWh. Not sure where that would go if I had an EV. The car I drive averages about 27 mpg, so that's about $135/month (at 3.65/gal).
Doing a rough calculation, my best case electricity cost for a Leaf would be about $35/month (10 charges) and the Volt (electric use only, 25 charges) would be about $48/month. These numbers will increase significantly in the coldest and hottest months (one source observed that the Leaf's range dropped from 100 to 20 miles on very cold days).
So, if I switched to either of these EV options, yes, I would save money, as much as $100/month, but in very hot or cold weather, that advantage could drop down significantly.
Would I switch to save that much money? Not on your life.
The convenience of being able to get a "full charge" in 10 minutes is worth every penny of the extra money I spend on gas.