I currently drive a 2003 VW Jetta TDI and a 2005 Jeep
Liberty CRD. Both get much better fuel mileage than their
gasoline powered counterparts. For instance, the Jetta
consistently gives me around 45 miles per gallon, with a
lead foot of course. The Jeep returns about 22mpg around
town, but is always over 28 and often over 30mpg on the
highway traveling between 65-70mph.
Both vehicles can run on biodiesel blends or straight
biodiesel. If you do not know what biodiesel is, then check
out www.biodieselnow.com or www.biodiesel.org. Basically,
its a fuel that is created from vegetable oil. This can
either be new oil from soybeans for instance, but many
people make their own using old frier grease from their
local fast food establishment.