Jim Norman of the New York Times has written a nice article about his own campaign to go green by converting a used diesel Jetta to run on vegetable oil. The piece covers the costs of converting, the hassles, which seem pretty minimal, and the head-in-the-sand attitude of the federal government, noting that "the Environmental Protection Agency recently issued a statement stating flatly that using vegetable oil as fuel is a violation of the Clean Air Act and that modifying a car for vegetable oil subjects the owner to a $2,750 fine."
What we need is for the government and car companies to figure out if large-scale production of veggie cars would help our environment and dependency on oil, foreign and otherwise, or whether if the mass amounts of soy needed would, in the end, rely on mass application of petroleum-based fertilizers, and whether the grease emissions, though they might be free of sulfur and low on carbon dioxide, would contain unacceptable particulate matter.
As it stands now the leading proponent of biodiesel is Willie Nelson, and what with his touring schedule, he can only do so much.
Norman's piece ends up noting that Rudolf Diesel originally intended his engine to run on vegetable oil, saying in 1912 that: "The use of vegetable oils for engine fuels may seem insignificant today. But such oils may become in the course of time as important as the petroleum and coal tar products of the present time."