Neil Young is setting out on a cross-country tour with a caravan of 17 vehicles powered by vegetable-oil-based "bio-diesel" fuel to promote his new film "Greendale" ....... here is part of a recent news story: LOS ANGELES, California (Reuters) -- Neil Young wants to talk about vegetable oil.It would be reasonable to expect that the rock 'n' roll veteran has more pressing matters on his mind -- he's just launched a month-long concert tour to complement the theatrical release of "Greendale," his first film in 22 years.But for anyone familiar with the project's storyline, which tackles such weighty subjects as religious warfare, corporate duplicity, the erosion of privacy and the destruction of natural resources, it will come as no surprise that its creator is eager to discuss not merely the tour itself but the tour's means of transportation."I have 17 diesel vehicles, and they're all running on vegetable oil farmed by American farmers," Young, one of the founders of the annual Farm Aid charity concerts, said in a recent interview with Reuters.