Ethanol fuel
Ethanol fuel appeared in 1980 in a modified Porsche 911, leading to a class win. Alternative biological fuel sources returned again in with Team Nasamax's DM139-Judd. In 2008, biofuels (10% ethanol for petrol engines and biodiesel for diesel engines) were allowed. Audi was the first to use next-generation 10% BTL biodiesel developed by Shell and manufactured from biomass.