The 230 mpg Chevy Volt

GM just said that their preliminary test on the 2011 Chevy Volt shown a health 230 mile per gallon in city driving. I assume this is great news comparing to the 14 mpg (city) on my old Explorer.

Wait a minute, this is a plug-in electric viehcle, what does the 230 mpg mean? My understanding would be if running purely on the gas generator, the car with run at 230 miles for each gallon of gas used. That will be translated into roughly 0.43 gallon or $1.3 per 100 miles based on today's gas prices of $3/gallon.

Not bad.

On the bottom of the Times' article, the author also mentioned that "GM... expected the Volt to consume as little as 25 kilowatt hours per 100 miles in city driving". Based on current California's consumer electricity price of 14.5 cents per KWH, it will cost $3.63 to drive 100 miles.

Now let's see whether I get this right:

According to this article, a completely gas powered electrical car will be about 2.8 times cheaper than the same car using electricity from the the grid.

There's something wrong with this picture or I am not capable of do 2nd grade math. If it's true, why would anyone want to plug in for 8 hours for each 40 miles single charge driving range?