The most aggravating thing about my 2005 Prius is the difficulty in getting a consistent fill of the gas tank. I know that "topping off" is not recommended, but today the automatic pump shut of engaged after less than 3 gallons. I was able to put another 6 gallons in manually at just a trickle. It's impossible to acurately calculate mileage for each tankfull. My last two tankfulls were at almost 48 mpg, this one (same kind of driving) was just under 32 mpg, as a result of a good fill. I guess I'll be topping off every time from now on.