It always amazes me that we continue to use deisel at all. According to the US dept of energy - alternate fuels all existing deisel powered vehicles can run on a mixture of deisel and biodeisel (made from virtually any vegatable oil source) and those built in the last ten years can be run on pure biodeisel. They put the cost at about $1.50 per gallon for fuel made from new vegetable oil and much less for that made from recycled. Who or what is preventing us using these currently available (renewable) fuels, made with current technology, which can be used by most current deisel engines without modification?