Seeing as the fez has a cable clutch, I'll take it you mean the brake master cylinder?? I haven't heard of any issues though.... can you explan it in a bit more detail?
There is a issue with the clutch cable coming off at the pedal which there was a recall for (Ford forgot to fit a retaining clip to the cable).
In regard to fuel consuption read this
thread
Also don't go by figures such as "I get XXXkmk per tank". A "tank" can vary up to 10lt of fuel, depending on when people actually fill up.
I recomend that you work out your exact "litres per 100klm" as discribed in the thread, then compare that to those real figures posted by a few of us in that thread i've linked to above.
