A Prius has to be driven differently from conventional vehicles to attain an outstanding mileage, and even if driven like normal cars, it still fares very very good, far above than what you can expect from a local sedan being driven under hypermiling.
I own a 2010 1.8 Prius S-Touring since January and over use have got used to coasting and other techniques but there are several times when I have to push it hard.
Here are the fuel averages I have got so far:
Best 20 km/l; Worst 15 km/l.
Best 24.5 km/l; Worst 20 km/l.