Eco-driving website Clean Green Cars found average CO2 emissions dropped by 12.07 per cent compared to the first three months of 2009 from 161.2 to 141.74g/km.
The drop in CO2 emissions across the Alfa Romeo range is partly due to the new Alfa MiTo MultiAir models.
Emissions from the MiTo MultiAir cut CO2 emissions in the MiTo by over 10 per cent to 129g/km in the 135bhp version.
Alfa Romeo has introduced a new, more efficient MultiJet engine for the MiTo, the sporty hatchback released in the UK towards the end of 2009.
The reduction in CO2 levels across the range means Alfa Romeo is now the 11th most environmentally friendly manufacturer, ahead of Mazda, Chevrolet and Ford.
However, the likes of Seat, Peugeot, Kia and Citroen are leading the way in the top ten manufacturers with sub-140g/km emissions.
Within two years, EU regulations state every manufacturer must have emissions below 130g/km. So far just three manufacturers have achieved this.
Fiat, with the help of the low-CO2 Fiat 500, enjoyed an improvement of 7.39 per cent compared to last year and now boasts emissions of just 124.61g/km across its range.
The figures show average new car CO2 emissions fell by 5.4 per cent in 2010 and the industry average is now 145.61g/km.
The scrappage scheme was responsible for the dramatic reduction, claims Clean Green Car, but it said the industry was on ‘broadly the right path’ to reach CO2 targets.