rstarkie said :
"The biodiesel there is a blend of used cooking oil and diesel."
Actually biodiesel is not a mix. It is a transesterification of fatty acids from fats or fresh or used vegoil. The fatty acids are essentially "cracked" into molecules nearly identical to petrodiesel molecules using methanol and lye..and sometimes sulphuric acid.
Although many diesel engines can be run succesfully in warm climates on a mix of prefiltered used vegoil and diesel...this is not biodiesel.
It is a common misunderstanding...that as a home "brewer" of biodiesel I thought might be best clarified.
And although less petroleum is used to make biodiesel than petrodiesel it is not , strickly speaking a "green fuel". The methanol used to make biodiesel (around 25% by volume) is made from natural gas.
Still this is a nearly 75% reduction in CO2 emissions compared to petrodiesel.
To run your Benz any greener requires a conversion to strait vegoil....and you still end up using 5-10% diesel for the required warm up and shut down period. Which is why I also make biodiesel. It lowers my petroleum dependance for transportation down to less than 3%.:p