These are generally reported by forum members to be 5-8% higher than measured by gallons into the tank and miles driven on that tank.
I would pass on all. The Prius line has been quite reliable, and most of the expensive stuff (powertrain) is warranted to 60,000 miles and 5 years. The hybrid components are warranted to 96 months, 100,000 miles (at least in the US non-CARB states).
Twenty tanks in, 13,692 kms (8,490 miles), and my awd Prius has settled in to averaging 3.7-3.9L/100kms (59-62.4 us mpg). I'm damn pleased with this car.
