That is incredibly misleading. The person in the article jammed his hybrid full of extra batteries to power the electric motor, then charges those batteries by plugging it in to an electrical source, which most likely gets its power from burning gas, oil, or coal.
"The extra batteries let him store extra power by plugging the car into a wall outlet at his home in this San Francisco suburb -- all for about a quarter.
He's part of a small but growing movement. "Plug-in" hybrids aren't yet cost-efficient, but some of the dozen known experimental models have gotten up to 250 mpg.
So then, the 250 mpg claim ignores the electricity added when he plugs it in at home. That's not really a relevant figure since additional energy is required to generate the electricity.