I just got my 2005 Prius a few weeks ago and I love it; however, a few days ago I read in the paper that Prius gas mileage will plummet when max AC in the summer or the defroster in winter is used. Since I live in Phoenix, I am worried! Is this true? Anything I can do to get better mpg? And please don't tell me to not use AC--110-degree weather won't allow that!