Supercars: more green, or just a little bit less brown?

British auto industry analyst Jato Consult's study has shown that although they're working from a low base and have some way to go in matching the makers of smaller, slower product, companies like Ferrari are registering among the ranks of the most improved.

But as the stakes rise with EU legislation imposing hefty fines on carmakers failing to meet emissions regulation deadlines, it gets harder to make sense of the hype. A case in point is McLaren's MP4-12C, scheduled for release in 2011, in direct competition with the likes of Ferrari's 458 Italia.

The 12C's mix of lightweight one-piece carbon fibre bodywork and a 450kW twin-turbo V8 gives it the highest specific power output and torque-to-weight ratio of any car of its kind -- which effectively means any car ever made.

Which McLaren Automotive CEO Anthony Sherriff turned into what might be one of the more disingenuous bits of greenwashing yet when he told British media: "A clear illustration of its special qualities is in the efficiency of its power delivery. With the 12C's power output of around [450kW] and its low CO2 emissions, it delivers the highest horsepower-to-CO2 ratio of any car on the market today with an internal combustion engine... and that includes petrol and diesel hybrids."

The Jato report, meanwhile, derives its conclusions from a mix of year-on-year emissions differentials and sales volumes for each model assessed. That is, they didn't just look at each model per se but as part of a fleet sold during the period in question. The essential issue addressed by such methods is which product does more harm to the environment: 500,000 minicars each putting out 100g/km of C02, or 250,000 medium cars each putting out 180g/km? Individually, the mini comes out ahead. But at fleet level, the midranger does.

Jato's methods gave Ferrari top billing (see table) with an average 40.4 g/km improvement in CO2 emissions among new cars sold in the first half of 2009 over the same period in 2008. At 9.5 per cent, this is up with the industry's strongest improvement levels, matching the performance of stressed-out volume brand Chevrolet over the same period.

Jato says Ferrari's net reduction figures put it "well on its way to achieving its stated aim to reduce CO2 emissions from 400g/km per vehicle to 280-300g/km, by 2012."

With the likes of Ferrari, Lamborghini, Bentley and Aston Martin dominating the ranks of bottom-dwellers in CO2 cleanliness, Jato head David Di Girolamo acknowledged that such marques are coming from a long way behind the best performers at the volume end of the market. "So they have more scope to reduce emissions than mainstream cars, but the speed with which they are improving their CO2 performance should be credited," he said in a statement.

He added that while sales volumes might be smaller, supercar brands still sell around 100,000 cars a year all told. Enough, he said, that "the days of supercar makers being excluded from the environmental debate are over."

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