Thirsty a4

[Amjad]

Hi, I've got 53 plate a4 1.9tdi 130bhp, just recently its gone heavy on fuel i was getting 38-40mpg round town but its now dropped down to about 33mpg i've had a diagnostic done which is all clear its drivin the same as before not smoking or anything can anyone out there help me please ?
Amjad :1zhelp:

[adamss24]

If you running on winter diesel fuel, expect an decrease in fuel economy.

[Amjad]

ive asked audi about winter diesel but they're saying it shoudnt affect the fuel ecomomy by that much. I dont want to be taking the car to audi yet because my local dealer charges 100 quid an hour any other suggestions what it can be ?