If you're new to TDI, start with Intro to Audi and VW TDI in the Navigation menu at left for why a diesel car may be in your future, why not a hybrid, and a quick list of pros/cons on each model. There are also model specific buying checklists/FAQ for prospective buyers and new owners.
If you have a question, ask in the forums. Registration is free and easy.
For TDI technical information, turbo theoy, biodiesel, and DIY "how to" articles, click on 1000
answered questions: FAQ and DIY.
The menu also has shortcuts to buying guides for current TDI models with reviews, exclusive technical information, features and options explained, pricing, and more. Buying guides for all older models are in the FAQ.
At the bottom are shortcuts to the OEM VW Audi wheel gallery and wheel, tire, and gearing calculator.