The red-and-silver Fiat brand has been declared Europe's greenest for the sixth year in a row, certified by independent organisation JATO Dynamics.
The brand secured the title by recording the lowest average CO2 emissions across the nine-model Fiat-branded range of just 119.8 g/km.
Helping the brand take the prize were the CNG (compressed natural gas) versions of its TwinAir models, which list CO2 emissions as low as 86 g/km.
In Australia, Fiat offers the petrol-powered light 500 TwinAir, with fuel consumption and emissions listed as low as 3.9 l/100km an 90 g/km.
Fiat will also bring the Panda to Australia this year, listing fuel consumption and emission levels on some variants as low as 3.5L/100km and 95g/km.
The past six years has seen Fiat reduce the average CO2 emissions of its fleet by around 13 percent - down from 137.3 to 119.8 g/km, although a record low of 118.3 g/km was recorded in 2011.
Mercedes-Benz, while finishing last among the top 20 green auto brands, saw the biggest improvement of all marques in 2012, cutting average emissions from 162.2 g/km to 147.8 g/km.
French brands figured strongly in the top five, with Peugeot and Renault climbing to second and third respectively, while Citroen secured fifth.
“The majority of volume brands have continued to reduce CO2 emissions this year, through a combination of smarter engineering and increased sales of electric and hybrid vehicles," JATO Vice President for Research, Gareth Hession, said.
“With the European Union’s manufacturer targets looming, it will be interesting to see if the regional variation starts to level out over the next 12 months."
The average CO2 figure for new cars sold in Europe in 2012 decreased by 3.9g to 132.3g/km, with every country except Belgium reducing its average carbon emissions through growing diesel sales.