Here are some back-of-the-envelope-type calculations. To make them, we needed a number to use for miles-per-gallon; this of course varies widely among vehicles, but let's use the 2004 Volkswagen Jetta TDI (diesel) as our example, which is said to average 44 mpg (diesel) when new. The same car with a gasoline engine gets 26 mpg. Biodiesel gets roughly the same miles per gallon as petroleum diesel. We encourage you to use your own figures and do calculations yourself.
In general, diesel engines get greater miles per gallon than equivalent gasoline vehicles.
retail price Biodiesel often costs a little more per gallon at retail than petroleum diesel. Here are calculations based on our Volkswagen Jetta example and example fuel costs (biodiesel prices vary widely; our $3.50 price comes from Durham's Bull City Biodiesel as of March, 2006):
|fuel type||$ / gal||miles / gal||gals / mile||$ / mile||$ / 25 miles|
|gasoline||$ 2.50||26||.038||.096||$ 2.40|
|diesel||$ 2.60||44||.023||.059||$ 1.48|
|biodiesel||$ 3.50||44||.023||.080||$ 1.99|