Just worked out my average for the last 427 mile tankful - a pleasantly surprising 37.1mpg! Interestingly (to me anyway!) I did a 60 mile trip into central London yesterday, that involved just over 50 miles of motorway/dual carriageway followed by 45 mins of very slow, stop/start traffic; plus, on the motorway the DPF did a regen. Unsurprisingly, the average (according to the computer) was 30 for those 60 miles. If this figure is accurate for what amounts to 15% of the total mileage; and bearing in mind that the average for the remainder (according to the computer) I would estimate to have been 36/37.....it suggests that the computer is perhaps very inaccurate - which I don't believe it is (from previous calculations).
So; I'm wondering whether the computer doesn't calculate the economy very accurately under certain conditions. The two conditions in question being:-
a) DPF regen
b) driving in very heavy city traffic.
I don't know at what point the computer measures the consumption of fuel, but can anyone confirm or rubbish my theory that the measurement loses accuracy when the car sits for a long time at tick-over, or is using fuel for a regen?