Does Willy Wonka know about this? From Boing Boing:

Sounds like an awesome band name, but chocolate biodiesel is in fact what one vehicle ran on, in a 4-week trek from the UK to Timbuktu. A group known as BioTruck modded a 1989 Ford Iveco Cargo to run entirely by biodiesel made from chocolate — specifically, discarded “waste chocolate” (*snort*) from a manufacturer.

Chocolate fuelled BioTruck makes it to Timbuktu on the worlds first Carbon Negative Expedition. – Link