The search for less-toxic alternative fuels is leading in many promising directions, one of which is bio-gas. Effectively a form of natural gas made from plants, the fuel was used this week to speed a modified B7 Audi A4 quattro to a new bio-gas world speed record of 226.6mph (364.6km/h).

Despite running on a mixture of methane and other gases generated by the controlled decomposition of grass clippings and sawdust, the Audi A4 used for the speed record generates a massive 700hp (522kW) from its overbored twin-turbocharged 3.0L V6 engine. What’s more impressive is that the powerplant is capable of producing upwards of 800hp (597kW), but output was limited this time ‘round to keep the transmission intact.

The project was completed as part of the Community Center of Excellence program at TUV Rheinland, with help in construction and execution from local tuning and transport companies. TUV Rhineland, the organizer of the record run, counts the result as a huge success. "We wanted to show," said Dr. Stefan Behrning, who oversaw the speed test for the organizers, "that bio-gas technology is highly suitable for ecological motoring without fossil fuels. Ecology and driving fun are not mutually exclusive."

While burning bio-gas does create atmospheric emissions, the process is CO2 neutral because the carbon dioxide released was captured from the atmosphere only months or years before by the fuelstock, rather than eons ago when the carbon in fossil fuels was captured.