I've had a Fiesta Zetec Eco 1.6 61 plate and curently have a Fiesta Zetec S TDCi 61 plate (both diseasels) so hopefully my figures will help!
The Eco and Zetec S both have different gearing, with the S being approx 300rpm higher at the same speed (Not sure where yours will come into that).
The Eco I had a high as 72MPG sitting at 60ish over a tank with 90% of that being major A & M roads, the lowest I had out of that car was 54MPG over a tank.
The Zetec S I've had 65MPG based on the same as above, however as low as 36MPG over a tank (Yes, I am 21)
If you limit the country road hooning and go as fast as the traffic in front, up to 3 points terroritry - I would expect 50-55MPG would be a fairly reasonable result.
Unable to report on remap side of life - my cars have been company provided and usually change every 12-18 months so wouldnt work for me really.