The prototype was created by GENeco, a Bristol firm specialising in sustainability and organic waste.
See pictures of the GENeco Bio-Bug and how the process works
The car can travel for 10,000 miles – one average motoring year – using an amount of excrement equivalent to that produced by 70 homes over a one year period. Its economy is 5.3 miles per cubic metre of biogas and it can reach a top speed of 114 mph.
The car is started with regular petrol, then automatically switches to methane once the engine has warmed up. Mohammed Sadiq of GENeco said: "If you were to drive the car you wouldn’t know it was powered by biogas as it performs just like any conventional car."
The gas used for the Bio-Bug came from the Wessex Water plant in Avonmouth and is generated through anaerobic digestion, which uses bacteria to process organic matter.
Before the gas can be used to power the car, the CO2 is removed to improve performance.