That's $6.30 to recharge a discharged Volt battery pack. Boy, look at those savings roll on in... Betcha that Volt will pay for itself in, umm, well, never at that rate.
Utilities offer special time-of-day rates for EV owners. If you do it just right then you can pay maybe 10 cents per kWh, and therefore your first 30 miles will cost you $2 to $3 - compared to $4.33 that I paid a few hours ago.
This would be great if the car itself is free or, say, is under $10K. But it isn't, and as result it will never be practical in financial sense, regardless of who you are and what is your travel pattern. If you drive a lot then you will be mostly burning gas (premium gas!) and if you drive a little then the car will rust and fall apart (7 to 10 years for batteries) before you reach the break-even distance.
In principle, an EV could be a good car for a city. But it has to be much, much cheaper than Volt and Leaf are. Perhaps they will become financially appealing if sold for under $10K. But that's not likely - the battery alone costs far more. We need better batteries before a pure EV becomes a viable option.