I own several VW diesel cars, two 86 Golf diesels and the 97 Jetta TDI. TDIclub is pretty much the gathering place although there's a decent discussion about diesel and TDI's on vwvortex.com in the technical section.

The timing belt change is expensive if you have someone else do it and it's particularly difficult on the A4 chassis cars (99.5+). The earlier A3 (97-99) cars are relatively easy and comparable to the earlier VW idi diesel cars / trucks. Same goes for the B4 (Passat) TDI cars from 96-97...pretty easy. I can say that the mpg for my TDI is excellent even if the car rides a little rough, then again I have 15" wheels and keep my tire pressure up there for easy rolling. I got 53mpg on a trip to Chicago and back this past summer pushing 70mph+ and I easily get 47mpg in the older diesel Golf running back and forth to work in town. The W140 is comfortable but not even close.

steve a

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Steve A
92 W140 OM603
97 VW Jetta TDI
90 Passat variant TDI 6 speed MT
94 Chevy K1500 6.5TD
05 E320 CDI
+ others