Accuracy of 2004 Prius gas gauge

Anyone else have a beef with the accuracy of the gas gauge on a 2004 Prius? When my 04's gauge is on the last light it will only take around 8.5 gallons into its 11.9 gallon tank.

Today, with only 4 of the ten lights lit, the computer indicated that I had used less than 5 gallons since the last fillup (that's miles since the last fillup/avg. mpg in that same time). If that's so, then it should have had something more like 6 lights lit. I've tried running it down to where the last light is blinking and it still only takes less than 9 gallons.

Something's not quite right here. Seems like the gas gauge is too low. Lots of trips to the gas station more than necessary.