I presently follow up all postings on a guy in Germany with an 7 series E65 Diesel.
He bought a large tank, buys oil at the oil mill directly which processes sunflower oil and rapeseed oil.
It started that he was upset with taxes on diesel oil. Then he went into a supermarket and bought some cases oil frying oil and filled his tank.
Car is running since more than 1 year without any problems.
He is not the only one doing that.
In trucks and large building oil heater boilers usually a lot of cleaned frying oil from big ready made food factories is used. Nice burning.
Bio diesel plant business is booming in Europe. Re-usable materials are subsidized a lot.
I know of a farmer here in Japan and some in Eurpe, they collect the gas from the cow and pigs sh*t, and they use the gas building up in the tanks to heat the complete house, the hot water system and he runs his car with that gas.
In Brazil they use socalled Gasohol since more than 30 years. Normal fuel is mixed with alcohol from sugar cane plantations.
Simple fermentation process.