2006 TDI: 36 to 30 MPG. Why?

[cep]

Originally Posted by boertje

That's what I thought too but the original post was September.

Oops. Missed that part. So much for the winter fuel theory.

[MichelleRoze]

Could still be winter fuel. The supplies usually change sometime from August to October. So it could still very well be winterized fuel which can cause up to a 5 mpg decrease depending on the area. I know here in Ga I start seeing mpgs dropping around september and we rarely have a cold winter that would cause any real freezing of fuel.

I don't know much about the new TDI engines, I have an ALH. Maybe try some fuel additives to help boost mpgs. I prefer Howe's anti gel and meaner cleaner together. Kept the engine running smooth and the meaner cleaner seems to clean the injectors out some to get better fuel economy.

With an automatic (mine used to be an 01M but now a 5 Spd) it seems the winter fuel hits harder. Also, don't know if it's the same with the DSG transmissions but see if you can reset the adaptation on the transmission. There is Eco mode and sport mode and it adapts with your driving. If you override the adaptation and keep it in Eco mode you can improve mpgs some.

Either way, hope you can figure it out.