I live in Essex, I drove on 4 miles narrow road then on the A1124, A12 and M25 to work and back total 83 miles same road 5 days a week, few traffic jam still average 38 then have done engine tuned and FAP remove now average 46 and I know you are right it is the cold use extra fuel but I will get more mpg in summer like 48-50? Because my friend own Peugeot 2.0HDI 110 saloon I think average is 51mpg but he did great 63mpg and 66mpg on 60 mph cruise to holiday in Scotland so that is 12mpg extra but my car only little extra about 3mpg with my 6 gears!!! he got only 5 gears!! see the different that is why I am not happy with it. My other old Fiat Punto HGT 1.9 sporting factory test is 53mpg and I got 65mpg average other my old Peugeot 306 2.0HDI average 67mpg Makes me wonder Citroen C5 engine management not good as later model.