Slashdot | Modified Prius gets up to 180 Miles Per Gallon: "The NY Times (free reg. required) reports in that some folks are not content with the no-plug-in rule that both Honda and Toyota endorse. By modifying a Prius so that it can be plugged in, Ron Gremban of CalCars states 'I've gotten anywhere from 65 to over 100 miles per gallon'. The article also reports that 'EnergyCS, a small company that has collaborated with CalCars, has modified another Prius with more sophisticated batteries; they claim their Prius gets up to 180 mpg, and can travel more than 30 miles on battery power.'"