German car manufacturer Audi says it has created the fuel of the future" made solely from water, carbon dioxide and renewable sources. The synthetic "e-diesel" was made following a commissioning phase of just four months at a plant in Dresden, Germany. Unlike regular diesel, the clear fuel does not contain any sulphur or fossil oil, while it has an overall energy efficiency of around 70%. Creation of the fuel, which Audi and Sunfire are calling blue crude, first requires heating water to 800C (1,472F) to trigger a high temperature electrolysis to break down the steam to hydrogen and oxygen. The hydrogen then reacts with the CO2 in synthesis reactors, again under pressure and at a high temperature. The reaction product is a ... synthetic fuel, which is free from sulphur and aromatic hydrocarbons, [that] is suitable for mixing with fossil diesel or being used as a fuel in its own right. Reiner Mangold, head of sustainable product development at Audi, said: "In developing Audi e-diesel we are promoting another fuel based on CO2 that will allow long-distance mobility with virtually no impact on the climate."