Poor fuel economy, 1.6

[Enright]

Hi all,
One of my neighbours has just bought an 04 plate 206 CC 1.6 Quicksilver.
I had a look over it at the weekend, and it generally seems OK:
55,000 on the clock, bodywork all straight, recently serviced, roof fully functional, and when I hooked up my PP2000 to it, it came back with no error codes stored.

Just a couple of small issues:
The brakes apparently squeal going downhill, although I noticed that it has recently had brand new pads on the rears and they've not put copper-slip on them.
It has a different brand of tyre on every corner (a pet hate of mine).
The clutch bite point is right at the top of the pedal's travel, and the release bearing sounds pretty noisy.
The trip computer hadn't been reset for nearly 6500 miles, and it said that the average mpg over this time was 31. I thought this sounded a bit low, but I'm only used to a car with less than half the mileage on it.
Might a set of spark plugs sort it out, or maybe an O2 sensor?
Anything that anyone else can throw into the mix that might routinely cause poor fuel economy?

[Capncol]

Firstly reset the trip and check again. Previous owner may had been a lead-foot and only driven round town.
PP2000 will tell you if O2 sensor is faulty.
Servicing a car you have just bought is never a waste in my opinion, so do that too.

FWIW, Vickies car averages 37MPG, mainly town, but reasonable motorway trips too.

[colinsp]

the average fuel consumption can be dragged down by the car idling. zero all the settings and try again.