What is the real petrol consumption of a Toyota Prius?

I get about 46 mpg (UK) - that's 36mpg (US) in the winter.

In warmer weather (autumn) I was getting around 54 mpg (UK) - that's around 41 mpg (US).

These figures seem way lower than the claims made for this car, which is still pretty new. During the summer of 2008 I managed to get the consumption "up" to around 54-55 mpg, though this is now dropping again as the cold weather sets in. At the annual service the garage informed me that my car was in a normal condition. In many ways this is still a great car, though the handling leaves something to be desired in windy conditions, and I wouldn't want to try to take bends at high speeds.