Good for you man!!
Volkswagens are awsome. I own an old VW Rabbit diesel but it's just the old standard 1.6L 4cyl.
TDI's I here are really cool. My mom tried one out when she went to buy a new VW Jetta. She said she didnt' get the TDI because when she drove it it just about made her eyeballs go in the back of her head! They've got lot's of power being a diesel.
My suggestion is to visit www.journeytoforever.com and click on the 5 gallon processor link. It will show you how with just a power drill and a five gallon steel bucket that you can make quality biodiesel every week!
Good luck