I bought my 2005 Prius just over three years ago, and am currently at about 77.5K miles, most of that put on in the first 2.25 years when I had a 65 mile one-way commute, split about 12 miles surface street to 53 miles freeway. At that time I was averaging 45 to 48 mpg per fill up, even (I confess) speeding much more than I should have. With that gas mileage, and before the price per gallon shot up so high, I was spending between 35 and 50 bucks a week on gas.
Now I drive only 6.2 miles one way, all surface streets, and am averaging 46 to 50 mpg per fill up. Twenty bucks now usually buys me two weeks driving, so I am getting about a threefold savings, even though price per gallon has been much higher this year.:cool:
I'll be interested in finding out if your change of tires will affect your gas mileage. I was cautioned that the installed tires were especially designed to improve gas mileage. But I think they were Yokohamas, so maybe your dealer installed the wrong brand on your car originally.
Also, I purchased early enough that I qualified for one of the car pool stickers, which was a big factor in my decision to buy the car, given the long commute I had back then. I was recently told that that sticker adds about $2k to the value of the car.