Interesting figures there. Never thought of it like that. How do they calculate those figures? Are they taken from actual road users or based on manufacturer MPG figures * average fuel prices?
I still think a 1.6 TDI will give you the best economy. But if you're looking for more of a balance against performance and don't want to remap, then I'd go 1.4 COD. You get the power of a 2.0 TDI, but if you drive it reaaaallllllly carefully you'll get the economy of a 1.6 TDI. So don't accelerate hard, stick to 70mph, don't put your foot down to beat a red light, stick to high gears etc. You'll get decent numbers.
For long mileage and motorway journeys a TDI will generally give you better economy. You'll sacrifice "refinement" (subjective) and get a tractor-like engine sound on a cold start but those low revs will keep you out of the petrol station.
I'd summarise that the 1.4 COD is a good balance but you risk getting poor MPG - it depends on your driving style. A TDI is probably more forgiving of an uneconomical driving style.