On the road I'm averaging around 13.5. Just spent two weeks at Fraser Island and it averaged 19.7 but that was with a lot of inland tracks so still pretty happy with it.
It absolutely hauls. Quite astonishing that a 2.5T vehicle can accelerate the way it does. Funnily enough it's the suspension that really is the best feature. Traffic calming is a thing of the past. It has active suspension and just eats up speed bumps, woop de doo's etc.
Best car I've bought since I got my GTS. It's a bit weird having the two parked next to each other though (Ford and HSV).