250 MPG Car

A patent has recently been filed on an electric car that will go highway speeds and last 40 miles (the average American commute) on gasoline or ethanol. They estimate that the average American will get 250 mpg. I'm skeptical as this seems like it would just increase your electric bill, but if the cost to charge it costs less than the gasoline, I could fill up a few times a year as my commute is only 6 miles or so. Sacramento even has a few parking spots at the mall and the airport where you can park your electric car to charge it.