I have a ScanGauge II (an older one). It is an OBD-II reader that looks like this:
Manufacturer's web site: ScanGaugeII - Trip Computers + Digital Gauges + Scan Tool
I plugged it into my Fiesta and it works. The Fiesta's OBD-II port is near the hood release.
You do need to configure it initially (engine size = 1.6L, gasoline (instead of diesel-a or diesel-b), metric vs. imperial units, lighting options, etc.). You may need to calibrate its fuel consumption display over a few refuelings.
The displays that I tried (which is not all of them) are:
Speed: Shows exactly the same as what the speedometer in the dash shows. (This is not true for all cars, some of which show a higher speed on the speedometer than what the ECU knows and reports through the OBD-II port.)
RPM: Shows exactly the same as what the tachometer in the dash shows.
Coolant temperature: When fully warm, coolant temperature fluctuates between 190 F and 195 F.
MPG: Shows calculation of instantaneous fuel economy. May be inaccurate until calibrated over a few refuelings. Interestingly, the Fiesta does not completely shut off fuel injection when coasting or braking in gear. On cars which do completely shut off fuel injection when coasting or braking in gear, the ScanGauge reports 9999 MPG (and 0.0 gallons per hour if that is displayed) during that time. The Fiesta reports numbers like 145 MPG (and 0.2 to 0.4 gallons per hour) under such conditions.
Fuel gallons per hour: Presumably the same calibration needed as MPG.
Throttle position sensor: seems to never go below 9 or 10. Perhaps related to the MPG never going to 9999 when coasting in gear?
Volts: 14.0 volts for the brief time I had that on.
The ScanGauge can also read generic codes, so that you can know the code behind a check engine light.
The main issue is where the put it if you want to keep it in the car semi-permanently. On top of the steering column is good place in many cars, but it blocks view of the fuel gauge in the Fiesta.

Manufacturer's web site: ScanGaugeII - Trip Computers + Digital Gauges + Scan Tool
I plugged it into my Fiesta and it works. The Fiesta's OBD-II port is near the hood release.
You do need to configure it initially (engine size = 1.6L, gasoline (instead of diesel-a or diesel-b), metric vs. imperial units, lighting options, etc.). You may need to calibrate its fuel consumption display over a few refuelings.
The displays that I tried (which is not all of them) are:
Speed: Shows exactly the same as what the speedometer in the dash shows. (This is not true for all cars, some of which show a higher speed on the speedometer than what the ECU knows and reports through the OBD-II port.)
RPM: Shows exactly the same as what the tachometer in the dash shows.
Coolant temperature: When fully warm, coolant temperature fluctuates between 190 F and 195 F.
MPG: Shows calculation of instantaneous fuel economy. May be inaccurate until calibrated over a few refuelings. Interestingly, the Fiesta does not completely shut off fuel injection when coasting or braking in gear. On cars which do completely shut off fuel injection when coasting or braking in gear, the ScanGauge reports 9999 MPG (and 0.0 gallons per hour if that is displayed) during that time. The Fiesta reports numbers like 145 MPG (and 0.2 to 0.4 gallons per hour) under such conditions.
Fuel gallons per hour: Presumably the same calibration needed as MPG.
Throttle position sensor: seems to never go below 9 or 10. Perhaps related to the MPG never going to 9999 when coasting in gear?
Volts: 14.0 volts for the brief time I had that on.
The ScanGauge can also read generic codes, so that you can know the code behind a check engine light.
The main issue is where the put it if you want to keep it in the car semi-permanently. On top of the steering column is good place in many cars, but it blocks view of the fuel gauge in the Fiesta.