In the 80 mpg equivalent I did not count taxes which are 36 cents including federal and Virginia taxes.
First sentence is true, second sentence is false. You are exactly right when you say you have to look at “how much energy it takes to create the electricity”. It is for that very reason that you ignore petroleum because it only contributes 1% of what “it takes to create the electricity”.
When they talk about petroleum generating electricity, they are talking about diesel generators. No one in the utility industry likes using diesel, it is only used for emergency backup or for the few hours during the hottest days of the summer when you need 101% of of your grid's capacity. Using petroleum (diesel) is the most expensive way of generating electricity that utilities can use.
So you are cherry picking the worst possible electricity generation source in order to use as a comparison. Nice try.
“If you want to use the power grid mix instead then you must use retail prices...”
Bingo! Now that is the correct way to compare. Hopefully now we can be done with this diesel-generated electricity nonsense.
“In the 80 mpg equivalent I did not count taxes which are 36 cents including federal and Virginia taxes.”
Are you exempt from gasoline taxes? Unless you would be using the Volt as farm equipment, the answer is probably no. Therefore, it doesn't make any sense to remove taxes. Instead we have to use real-world gasoline prices and compare them to real-world electricity prices. My “60% less for electricity” figure was admittedly based on gas prices before the recent drop in oil prices (which most people believe is temporary).
Regardless, it sounds like you live in an area of the country with some of the cheapest gas. Good for you. Your savings for switching to electric car would be less than the rest of the country.