Citroen Airdream

On paper, few manufacturers can match Citroen’s green credentials. Take a look at the French company’s current model line-up, and you’ll find 17 cars which emit 120g/km or less of CO2.

That’s the level European regulations are demanding as an average for all makers by 2012, so the brand is already ahead of the game.

The new Airdream sub-brand is reserved for the greenest Citroens – cars which not only put out that low level of carbon, but are also designed to be at least 95 per cent recyclable and are assembled in a factory which complies with strict international environmental legislation.

At the moment, only the diesel-powered C3 1.4 HDi supermini qualifies, but bosses are working to introduce more Airdream variants in the coming months and years.

Yet that’s not to say standard models aren’t clean-running. For instance, the tiny C1 city car has the lowest emissions and best economy of any Citroen – its 1.0-litre three-cylinder petrol unit puts out 106g/km and returns a claimed 62.8mpg.

Further up the range you’ll find the C2 supermini, complete with a frugal 1.4-litre HDi diesel engine.

This smooth and torquey powerplant gives the model decent performance, plus a CO2 output of 113g/km.

Go for the C4 family hatchback or C4 Picasso people carrier, and you can specify the hi-tech Electronic Gearbox System (EGS).

When mated to the 1.6-litre HDi diesel engine, this paddleshift-operated five-speed automated manual transmission is claimed to deliver an increase in fuel economy of up to five per cent over a traditional manual gearbox.

However, Citroen’s environmental commitments don’t end with the efficient drivetrains it uses. It has also focused on the construction of its cars, and as a result, at least 85 per cent of the materials that make up the firm’s models are recyclable.

BEST ECO BUY: C1 1.0