I have an A6 2.5 TDI (Bj. 1998) with the V6-150 HP AKN engine. At first I had a tank for 850 km, but then I screwed up to a maximum of 900 km. However, since about summer 2004 I observed how my fuel consumption increased more and more. At first it was enough for 750 km then for proud 700 km and meanwhile 650-700 km. According to FIS, the consumption in winter 2004 was 7,4 L, but in summer 8.5 and mid-term The 9 L air filter was changed by me, unsuccessfully… Additives such as cleaners of diesel lines used, unsuccessfully…. In addition, I have been observing an overly vibrating engine start since 1 month in the morning especially when gas is given directly after the start. At the cold start you feel next to the vibration, as if the engine would swallow unsolicited diesel. The whole thing becomes normal after 10 minutes. I don’t think the weather plays a role in the rise, because it does The driving method has always been the same. what possible defect or problem could be the cause? Thank you in advance.