BMW X1 sDrive20i SE Auto
- OTR £31,475
- Petrol, SUV, sports activity vehicle
- 1998cc (2.0 litre), Automatic 8-speed, 5 door
It is widely accepted that the official data for emissions are far from accurate, measured as they are in the laboratory. The NGC Emissions Calculator therefore uses Real Driving Emissions (RDE) where available to provide an accurate indicator of environmental impact.
Real-world emissions and MPG are estimated using the EQUA Indices for Air Quality (NOx), Carbon Dioxide and Fuel Economy as provided by Emissions Analytics.
Next Green Car has partnered with Emissions Analytics to improve the NGC Emissions Calculator through the use of model specific Real Driving Emissions (RDE) data for NOx, CO2 and MPG. This data is measured using portable testing equipment during real-world driving.
In cases where RDE data is available, the NGC Emissions Calculator uses a vehicle’s EQUA Indices (banded) as measured in real-world driving conditions by Emissions Analytics. In cases where no RDE data is available, the emissions calculation is based on official test data which is multiplied by a ‘conformity factor’ to estimate real-world emissions.
To find out more about Emissions Analytics’ EQUA database, or to view the EQUA Indices for a specific UK model, visit the Emissions Analytics website.
How we calculate CO2, NOx and PM emissions
The calculator estimates total emissions of carbon dioxide (CO2), nitrogen oxides (NOx) and particulates (PM10). The calculator also provides a breakdown of total emissions according to direct (tailpipe emissions) and indirect emissions (emissions generated during fuel and vehicle production).
Direct tailpipe emissions are calculated by multiplying the official or real-world emissions figure (in grams per km) by the journey distance or mileage (in miles), and a factor representing driving style (‘Normal, ‘ Aggressive/Fast’, ‘Eco-driving’).
Indirect fuel production emissions are based on published data quoted on an energy delivered basis (in grams per giga joule). These values are then multiplied by the vehicle’s official or real-world fuel economy (in litres or kWh per 100 km), the journey distance or mileage (in miles), and a factor representing driving style (‘Normal, ‘Aggressive/Fast’, ‘Eco-driving’).
Indirect vehicle production emissions are estimated which represent emissions associated with the vehicle’s manufacture. The approach is based on a per kg emissions for each vehicle type (petrol, diesel, electric, etc) which is then multiplied by the mass of the model selected.
In cases where real-world RDE data is available, the estimates for CO2 emissions have a high level of confidence. Where no RDE data is available, the estimates are based on the average discrepancy between official and real-world performance, and average correlations between emissions, driving style and road conditions.
For more details of the methodology used to calculate emissions, download the PDF document: NGC Emissions Calculator Methodology 2016