This is a great site for gaining insight into how to fine tune your driving habits and car to get great mileage. There is lots of good info on a multitude of topics. You may want to go to www.tdiclub.com
as well though, as the TDI is quite different from a gasser. There are some techniques that cross over between gassers and diesels, but there are some specifics that you would be better reading up on over at tdiclub.
I'd say that you should balance your time between the two sites.