Well, I had to fuel up on the way home from work tonight. The MFD showed 35.6 mpg at the filling station, so that's what I went by on the tank info, since I have no idea how "full" the dealer actually got the tank. Now that I know how full the tank really is, I'll be able to get an idea as to how accurate the MFD is in comparison to the calculator. One thing I'm very happy to not have, is that infernal bladder that Toyota puts in the Prius.

So far, I'm already showing 38.5 mpg on the new tank. However, there's less than 20 miles on it. I'm truly curious to see what this vehicle will be capable of, once it's broken in.