According to the data for H1 2010, almost 60% of European new cars are now at or below the 140g/km CO2 level, a 6.7% improvement vs. FY 2009, seeing the market share of low emission cars with up to 120g/km CO2 grow by 5%.

In particular, the market share of the sub-100g/km emissions band is also increasing, as more mainstream models, such as Ford Focus ECOnetic and Volkswagen Golf BlueMotion, achieve this level.

Top of the list for low-CO2 countries is Portugal, with an average new-car CO2 figure of 129.3g/km, ahead of both France and Italy, which are known for favouring small diesel cars.

The greatest improvement in national average CO2 figures for H1 2010 were shown by Greece (-12.5g/km) and Ireland (-10.2g/km), but for very different reasons. Ireland's CO2-based vehicle taxation system has generated a significant shift in buyer behaviour, towards smaller, more efficient cars. Meanwhile Greek car buyers have been particularly hit hard by the recent recession, with simple economics reducing demand for larger cars, particularly SUVs.

‘We have seen a significant reduction in average, volume-weighted CO2 output in Europe – triggered by a perfect combination of manufacturer effort, macro-economic conditions driving demand for greater efficiencies and taxation schemes to shift buyer behaviour,’ commented David Di Girolamo, head of JATO Consult. ‘The litmus test will be to see if this pace of change continues as consumer confidence returns.’

Fiat retains the crown as the lowest CO2 brand in Europe, with a H1 2010 average volume weighted CO2 output of 123.5g/ km, improving a further 4.3g/km on FY 2009.

Toyota remains second overall, helped by its Prius being the lowest overall CO2 five seat car, and continued strong sales of its efficient Yaris and Aygo models.

Fiat also took the title of the lowest CO2 model, with the Fiat 500 improving 3.9g/km. Last year's leader, the Toyota Yaris would have slipped to second place, but a slight fall in sales in the post-scrappage market dropped it just outside of the top 20.