NEXT Green Car, the UK’s No.1 green car website, has updated its NGC Rating to account for known differences between official and real-world CO2 and NOx emissions.
The update, which has been implemented in light of the recent Volkswagen emissions scandal, allows car buyers to calculate total carbon dioxide (CO2), nitrogen oxides (NOx) and particulate (PM10) emissions for any new or used UK car or van. Official and real-world driving emission figures can be established according to the distance covered, and driving style.
Next Green Car has created the update because of the growing differentiation between official and real-world test data. Although ‘rolling-road’ tests were originally sufficient as a way of estimating on-road emissions, some practices employed by a number of manufacturers has now rendered many of these test results invalid.
To accurately estimate real-world emissions, a series of correction factors are applied to the official test figures. Real-world CO2 emissions are estimated by applying ‘mpg factors’ published by the ICCT1 for fossil-fuelled cars.
For NOx emissions, real-world figures are estimated by applying ‘conformity factors’ to official figures.
The NGC’s update, therefore, more accurately displays the emissions of different fuel and vehicle types. When compared to the original score, the new NGC rating penalises diesel powered vehicles by around four points thanks to the higher estimates of NOx emissions. Ratings for electric cars, meanwhile, remain largely unchanged.
A model-specific Emissions Calculator has also been made available on all individual model pages, with the same methodology being used for all engines, including pure electric and plug-in hybrid vehicles, alongside conventional petrol and diesel models.
Dr Ben Lane, managing editor of Next Green Car, said: ‘In part a response to the VW Group emissions scandal, we have updated the NGC Rating to account for the higher CO2 and NOx emissions associated with real-world driving.’
On SuperUnleaded.com: 150mph Blow-Out Will Make You Want To Check Your Tyres