[fiestaz]

It would be interesting to know how much fuel is going into your tank (in Litres) vs kilometres to then do the calculations manually. From what you and others have said, it sounds like the trip computer is giving you expected figures from the 2.0T mondeo.

The running like crap thing is odd. Someone else may know better with the Mondeo but what about a computer reset via battery disconnect? Or even battery on the way out? I know many cars get weird gremlins when the battery is not too happy or coming to end of life.