Have a look at this thread to see the correlation between vehicle mass and actual real world fuel consumption for cars with 3 cylinder 1 litre engines.
http://ecomodder.com/forum/showthrea...ion-34666.html
The ford focus with 85kg driver/fuel is 46% heavier than Mitsubishi Mirage with 85 kg driver/fuel.
This results in an increase in real world fuel consumption of 39%.
Ideally the car should have been lighter but failing that the engine should have been bigger.
Interestingly, Ford has now stretched the engine to a 1.1 but so far only naturally aspirated versions of it has been released in the Ford Fiesta.