that is pretty good milage but you must drive like a priest to get it. I almost alwas drive with the Extra Power switch turned on and almost always using the manual shift mode (revving it up high close to 4000 RPM before shifting to a higher gear). I drive it like a meniac and get around 13.5 l per 100 Km (17.4 mpg).
In these parts of the woods where I live you can't maintain a constant speed because of traffic and road conditions. Never got to use the cruise control. For the size of the car, all that torque 286hp at 3,600 rpm and 479lb-ft from 1600 to 2800rpm, and accleration of 0 to 62 mph in 8.2 seconds (1 second faster than the 4.7L gasoline engine), I think 17.4 is a great milage.
I drove around 100 kilometers watching the consumption indicator and I got 9.8 litre/100 km. But that is some boring driving. The diesel 200 LC is the funnest thing I ever drove. I had a 100 LC for three years, also diesel, but this 200 is amazing.