Sports cars, reputed for being energy guzzlers, are now trying to boost their green credentials as they seek to attract environmentally conscious consumers and meet new climate standards.

At the Geneva Motor Show, Ferrari conscientiously draped signs on its new models saying that the vehicles' carbon emissions have been cut by 30 percent.

The F12 berlinetta, a 12 cylinder car with 740 horsepower, is equipped with a system which automatically halts its engine at red lights or in traffic jams, thereby saving some fuel.

The brand is also developing a hybrid model, the F599 HY-Kers, although it is still a prototype at the moment.

If sports carmakers are making this effort to go green, it is partly because they are driven by new and tougher environmental standards in Europe.

By year end, carbon emissions of new cars would have to be below 130 grams per kilometre.

On 2015, all cars sold must reach this target, or their manufacturers would be heavily fined.

Some firms are also pushed by consumer demand to develop greener sports cars.

"We have for example, bosses of companies which respect environmental standards and who therefore do not want to be in a paradoxial situation in which they are driving a highly polluting sports car," said Eric Mathiot, marketing director of Exagon Motors.

The French maker has therefore come up with the Furtive eGT, a racer with two electric motors of 125 kilowatts each.

To compensate for the massive 480 kilogramme weight of the battery, the car's chassis and body are in carbon.

"The car accelerates from 0 to 100 kilometres per hour in 3.5 seconds, that's as fast as a Lamborghini Aventador," said Mathiot, adding that about 60 orders have been placed for the 300,000 euro ($395,140) vehicle.

The batteries propelling these engines are also unlike those filled with lead and acid, said Stefan Suckow from Johnson Controls, a US firm that makes batteries for Daimler, BMW and Ford.

"Everything can be recycled," he said, in particular the copper, the cobalt and nickel from these batteries which are built to last ten years.

But some sports car makers still believe that in the necessity of unleashing the potential of such vehicles, whatever the environmental cost.

With 1,200 horsepowers, a 7.9 litre engine and a maximum speed of 410 kilometres per hour, the Bugatti Veyron 16.4 Grand Sport Vitesse is no model of sobriety.

The consumption of the "most powerful tourism vehicle in the world" reaches 37.2 litres for every 100 kilometres in the city and its carbon emissions stand at 867 grammes per kilometre on urban terrain.

"It's not that Bugatti does not want to go into this subject (environment) but the brand is considered as VW's spearhead and therefore it needs to demonstrate our savoir-faire technique," said a spokeswoman.