Don't quite agree with C&D that the Explorer is that bad on the highway. Obviously, it's big and heavy and not great at twice the speed limit, but it's a brilliant long-distance cruiser. I do agree that the CX9 drives better than any seven-seater has reason to.
Depends on your traffic. In the right (or wrong) traffic, you can get the 3.0 D4D down to 5 km/l, too.