I know the computer is not 100% accurate, and I realise it can be adjusted. I reset it every time I fill up.
It seems to be getting worse. It's still showing a fairly steady 29 mpg average and has been since I got the car. That was a always a bit optimistic compared to my calculated mpg, but now I am down to about 24 actual and the computer is still reading about the same!
My question is, what drivetrain faults could cause this?
For example, does the computer count injector pulses to decide amount of fuel delivered? So, would a knackered injector cause this?
Also, could a slipping clutch cause this (I doubt it!)
Any other ideas?