I do not have a Fiesta bud but have a Focus 64 plate zetec s tdci 1.6 and love it, don't think the fiesta has the 6 speed box in them but dirt cheap to run.
I bought mine new pre registered in January this year with 6 miles on clock, will be turning 19k this weekend and I get 600-630 miles from a tank its only about £50 to fill it up. Its never skipped a beat computer reads about 61.4 mpg that's motorway plus heavy bypass traffic commute return at night. My works a 74 mile round trip daily.
Just had mine remapped 2 weeks ago was 115 standard, company that remapped it says average gain is about 30-32 horse and 55-60 torque. Deffo pulls away much sharper, You could actually stall these pretty easily if you tried but takes away like a different car.
By the way I came from a 57 plate 2.0 TDI 170 Audi A4 qauttro and do not miss that pile of shite in the slightest.