On Jan. 12, 2006, the Environmental Protection Agency announced that it plans to change how it calculates fuel economy for new cars and trucks to more accurately reflect the real-world mileage experience of American drivers. The EPA has increasingly come under criticism for outdated procedures that overestimate mileage by as much as 50 percent in some cases. Consumers are likely to see lower, more accurate numbers on window stickers of model 2008 vehicles arriving in dealer showrooms in the fall of 2007.
EPA mileage numbers are inaccurately high for all cars, not just hybrids. The EPA test procedure, originally developed in late 1960s, is out of date.