2006 Prius here, I know my gas gauge is messed up but I don't know what's causing it. The first 8 bars on the gauge disappear super fast, then the last 2 bars last a long time. When it hits 2 bars I go to refill it and it takes 4-5 gallons at most. All 10 bars get filled when I refill it so I know it's at least somewhat working right. Also I already tried resetting it using the gamepad easter egg type ODO reset trick lol, but stays the same. Any ideas?
From what you're writing, it may be normal. Try another gas pump and see if you get different results. This is the bladder tank, so it can fluctuate