Quick question, which I couldn't find the answer to by searching.

 

What does the trip computer in the PID use to work out fuel consumption, range etc? The GPS along with the fuel gauge? Or the odometer and tachometer along with the fuel gauge?

I would imagine it reads from the ECU.

as the figures on the PID always match the onboard figures I would say it is reading the ECU

 

if it was using GPS etc you would expect to see a difference in the figures

Its using the OBD2 data, a standard set of info agreed by manaufacturers to provide a standard cable interface and figures

take a look at this app for phones to see what sort of things it sends. eg it includes acceleration and lots of other stuff. the PID then details it out.

You can buy your own ODB connector (no idea where it is in the citigo, i assume under the gearstick) and run apps on your phone!

 

https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en_GB

 

It makes taking the car to an indepantant garage much easier.

Shame it's not for iPhones :(

there are similar apps, just search for obd2