The ScanGauge works fine in a Fiesta.
Interestingly, I never see 9999 in the instantaneous MPG or 0.0 in the GPH (gallons per hour), even when coasting in gear. In a previous car, I would see that when coasting in gear (indicating no fuel being injected under those conditions) until pressing in the clutch or the RPM reaches idle RPM.
Only thing is, there is no obvious best place to put it:
* On top of the steering column: covers up fuel gauge and parts of speedometer and tachometer.
* On the shelf in front of the SYNC display: covers up some of the SYNC display, though otherwise a very viewable location.
* On top of the left side of the dashboard: a somewhat less natural place to look. Probably the best place for a semi-permanent mount, if you don't want to cover any of the SYNC display.
* In front of the shifter: an even less natural place to look, and partially covered by the shifter (manual) in 1, 3, or 5.