Hi
I've got the 140 4x4 diesel and my fuel consumption equals that of Wakev, I've also driven the 1.2 (but only for around 250 miles)
If you have a low annual mileage and make short stop start journeys I would not go for a diesel as the DPF would probably not like it. If on the other hand you will be making fairly long journeys, (I average 15 to 18000 miles a year with regular trips to Germany),carrying a full load, or driving up a lot of hills I would go for a diesel (or at least a larger petrol engine).
As I had gone from a larger diesel engine to the 1.2, I found it much slower with it struggling up hills, the fuel consumption was also heavier than my diesel.
In defence of the 1.2, the engine was very quiet and lively for it's size. Whichever one you go for make sure you have a heated windscreen.