The equivalent spec Fiesta has a stated 0 - 60 time of 13.3 and a combined fuel consumption of 50.4mpg AND CO2 of 129, which equates to £100 per year for road fund licence. The 208 whilst slower has a combined fuel consumption of 62.8 and emits only 104 CO2's which means only £20 per year. You want a faster car, BUY A BIGGER ENGINE!
I would prefer to pay less to run the car than get to 60 0.7 seconds quicker, which I guarantee you wouldn't really notice anyway.