The EQUA CO2 index has been established by Emissions Analytics, a specialist in real-world, on-road vehicle emissions measurement and analysis, covering the European Union and the United States.
The new index complements the company's recently-launched EQUA Mpg, which provides real-world fuel economy figures for more than 60,000 cars.
The EQUA CO2 index has a simple scale that denotes each car's rating regardless of fuel type. Ratings range from A1 — the best — to H5.
The 'A1' rating is currently only achieved by one vehicle, a Citroen C3 diesel — 'A' representing the best absolute emissions, and '1' the accuracy factor.
Taking the car market as a whole, average real-world emissions of Euro 6 cars are 181g/km of CO2 — a figure that hasn’t improved since the previous Euro 5 generation of car.
Compared to the current legal fleet average target of 130g/km of CO2, the new EQUA data shows that this legal target is being exceeded by 39pc.
Average CO2 emissions from new petrol cars have fallen by 6pc since 2012, when Emissions Analytics started collecting data. However, over the same period, the average emissions from diesel cars have risen by 5pc.
