Same here, I do quite a bit of city driving and know I'm getting 40-42mpg but the trip computer says I'm struggling for 37mpg. Other AO's say that their trip's are pretty much bob-on though, my 147 has had MAF/EGR problems which affected fuel economy. Repairing them solved the economy issues but not the trip computer's figures so maybe a simple ECU reset will solve it. Hope you get it sorted.Now, here's an odd thing - the average fuel consumption on the display always settles out at about 37mpg or so. But I've calculated the real mpg on 3 consecutive tanks of diesel and it's been 47, 44 & 46 mpg. Yes, I can do sums, so what's going on?