hi there i have 2003 2.0 hdi c5 had no probs with till the other week, its lack of power up hills it goes ok very slow then it takes off witch it has never done before and the fuel goes down faster as well i havent changed the fuel filter for about a year dont no if it could be that but i used to get 80-90 mph for £10 and now i get 50-60 for the same and i no fuel cost change but only a couple of pence