$800 is for a month of electric (PG&E) or $9600 per year, plus the $900 for the batteries per year.
That means about $10,500 a year, which is equal to about 210 fill ups of a 20 gallon tank at $2.50 a gallon. That doesn't sound so reasonable.
Of course these numbers are all based on someone's guesstimate of a $800 per month electric bill. I have no idea whether that number is reasonable or not.
And who is Viola??? (kidding)
--$800 is for a month of electric (PG&E) --
If you drive 24,000 miles per month ...
No, I didn't miss anything. The poster said that gasoline was $800 a YEAR, that, combined with the amortized $7000 of the battery over it's 8 year life is a total of $1700 a year.