Video (2min 19sec) of Christina Sporong of Taos, NM who runs her truck on biodiesel.
"Well what's great about it is you use less of the fossil fuel and the emissions are significantly less, so you're running a cleaner truck. You can get biodiesel from people around town here who have big tanks, like 300 gallon tanks, and you can just buy in to their share. Or you can buy it at the pump down in Santa Fe. B20 they sell there. B20 means it's twenty percent biodiesel, meaning 20% processed vegetable oil. Usually you can get B20, B50 and B100... B100 in the winter is problematic because it congeals. So we use mainly B50 out here..." Biodiesel refers to a diesel-equivalent, processed fuel derived from biological sources (such as vegetable oils), which can be used in unmodified diesel-engined vehicles. It is thus distinguished from the straight vegetable oils (SVO) or waste vegetable oils (WVO) used as fuels in some modified diesel vehicles.
Read more about Biodiesel at Wikipedia