This actually relates to my Fiat punto everyday car I use for work, but the principal is the same I guess.
Car has only done 10k miles from new but I have noticed a reduction in the fuel economy on the average MPG on my trip computer. Car is boked in for a service next friday so no biggie.
Anyway I wanderd if this reduction could be contributed to :
A) Colder weather recently (thought the ECU would adapt to this)
B) Does need serviced, new plugs etc...
C) Different Fuel, even though i fill up at the same garage every time
D) Maybe i've just been thrashng it for the last 2k miles and haven't noticed...

No big deal, i just wandered what your thoughts were, as I'm bored @ work