 I purchased a high end Prius with the all the features in 6/08. Started out getting 46 mpg. to 44mpg.Then 3 month later it went down to 30mpg to 34mpg. tops. Brought back to dealer they checked it out & said they could find anything wrong. My Nav unit reads I'm getting around 36 mpg. But when you do the math after a fill up it's getting 30 to 32 mpg.