Geneva  - The Swiss tuning firm Sportec is offering a Porsche 911 with compressed natural gas (CNG) drive that it claims offers both more power and reduces carbon dioxide emissions in comparison with the conventional model.

Fitted with two additional turbo loaders, the Porsche SP 550 mean & clean boosts the power unit from 480 to 550 hp. A special air filter system provides additional cooling. The six-cylinder engine electronics have been reprogrammed improving acceleration from zero

to 100 km/h in 3.7 seconds with a top speed of 331 km/h.

In addition, Sportec offers an aerodynamic package that includes optimized front spoilers and rear wing in GT racing style.

The CNG drive gives the driver the option of switching from petrol to the more eco-friendly natural gas at the press of a button. Sportec did not provide figures for carbon dioxide emissions, but said they were "substantially" lower than for the standard Porsche Turbo.

Lower fuel consumption is also achieved with the Michelin Pilot Sport PS tyres that have 19 per cent less rolling resistance, according to Sportec.