before taking my 2008 Octavia vrs tdi cr dsg back to the dealer, does anyone know why the average mpg would have dropped from around 46mpg to 38mpg following its first service early in October? I had been hoping it would improve again- but it hasn't.

Cold weather, incorrect tyre pressures...heavier right foot :yes:

tyre pressures spot on, weather in october was fine, driving style remains the same- as it has over the last 2 years with this car

We get a lot less mpg in cold weather with both our cars but i've also found the cars seem very sensitive to air filters so i would think about trying a new one to eliminate that

Thanks for that- air filter fine, I suppose what I am asking is- why has my cars fuel consumption worsened so much following its first service??

I think you need to ask this question to the garage, hopefully they are a helpful and understanding garage and won't just fob you off! They might have knocked/damaged something or changed something which has caused this drastic change in mpg. Think that is the only place you will get an answer you like