Last September we drove down to Assisi in Central Italy a round trip of 3000 miles. This was a mix of motorways, main roads, town driving and local running about for a week whilst we were there. The journey included a spell on the German autobahns at 100+ mph (max 120mph just to see what the car was like - very impressed!), down through Switzerland and over the St Gotthard Pass (so plenty of up and down in the mountans - again very impressed!), Italian autostrada where the average spped of the traffic seems to be about 90mph! and, as I said, a week of local tootling around followed by the reverse journey home. The average fuel consumption for the holiday was 31.5MPG. (This was with the outside temperature mainly in the upper 20s)
Last Sunday we drove over to Felixstowe and back from Milton Keynes in the falling snow and freezing temperatures - a round trip of 240 miles with an average fuel consumption of 27.4MPG.
Just popping up to the shops and back in the winter with a cold engine gives about 15-20MPG.
Best average consumption to date was a drive from Norwich to Milton Keynes 2 weeks ago (outside temperature about 10 - 15 degrees) using ordinary country roads where possible and a very light foot giving a figure of 35.1MPG!
To sum up - it all depends on the type of journey, the length of your journey, the outside temperature (and whether or not you have the cabin heater on or off), and most importantly your style of driving!
Overall we have been very impressed with the fuel consumption, especially as there is no compromise with the performance of a vehicle of this size and comfort.