This is such a non-story it's unreal.
I have a Peugeot 3008 1.6 Diesel*, and the official figure for the MPG is 55. This is mixed with urban driving and motorway driving. The problem is, after 2 years of owning it, the best I've ever got from it was 53 MPG by driving totally on the motorway (Birmingham to Glasgow). That was me driving at 55mph too. With my daily driving I get 40 MPG, and that's a mix of inner city driving and 70mph carriageways.
So to say Mitsubishi "cheated" results that no one is EVER going to get near anyway is irrelevant really. Everyone knows the official figures are unobtainable, so it makes no difference at all that the figures were cheated.
* soon to be replaced by a 1998 Toyota Corolla. Because I want reliability, not French spit and duct tape engineering.