That article really piqued my curiosity. I'd be more interested in making regular biodiesel than running the straight oil. Producing biodiesel from waste or clean vegetable oil is actually pretty straightforward and very similar to the process for making soap. One of the major by-products is glycerin. Many biodiesel producers have been using the glycerin to make and sell an effective degreaser similar to GoJo.

Interestingly enough, there's an '83 2-door VW Jetta diesel for sale nearby. Really nice shape and 1-owner. Very tempting...