Which main pollutants, related to vehicles emissions, are regulated at the EU level?
Carbon monoxide (CO), oxides of nitrogen (NO and NO2, collectively referred to as NOx), unburnt hydrocarbons (HC), and particulate matter (PM) are the main pollutant emissions deriving from petrol, diesel, and alternative-fuel engines. These pollutants emissions are all regulated by the ‘European emissions standards’. Carbon dioxide (CO2) is not a pollutant as it doesn’t cause health problems or harm plants and animals in a direct way, but it is the main greenhouse gas. An increase in CO2 concentration in the atmosphere contributes to global climate change. For this reason, the European Union also sets specific CO2 emissions targets for vehicles through dedicated legislation.
What is the link between fuel consumption, pollutants and CO2 emissions of my car?
Fuel consumption and CO2 emissions are directly related; the more fuel a car consumes, the more CO2 it produces. The explanation is simple: fuels contain carbon which produces energy when burnt. This energy moves the vehicle. The product of burning carbon is CO2. The carbon content of the fuel is characteristic for each fuel type (petrol, diesel, etc.), which means CO2 emissions can be easily calculated if the fuel consumption and fuel type are known. In comparison, pollutant emissions from cars (NOx, HC, CO, and PM) are more complex, since they depend on many factors, not just on fuel consumption. In diesel cars, for example, NOx emissions depend mainly on the operating conditions (temperature - pressure) of the engine and on the efficient operation of ‘after-treatment’ systems of the car.
How are the official fuel consumption and CO2 emissions of my car determined?
Official fuel consumption and CO2 emissions are determined under controlled conditions in a laboratory using a ‘chassis dynamometer’, which is a sort of treadmill for cars. Cars are driven on the chassis dynamometer following a precise sequence of accelerations and decelerations called a ‘cycle’. Before each test, the chassis dynamometer is calibrated based on the mass of the vehicle and on other resistances experienced by the vehicle when driving on the road. Up to 2017, the cycle used for measuring official pollutant emissions and fuel consumption of cars in the EU was the New European Driving Cycle (NEDC). However, the NEDC produced fuel consumption and CO2 emission values that were increasingly different from real-world figures. Because of this, the NEDC is being gradually replaced by the Worldwide Harmonised Light Vehicles Test Procedure (WLTP), which produces more realistic results. Furthermore, the Real Driving Emissions (RDE) test, an on-road testing procedure, has recently been added to the certification procedure of cars to cross-check pollutant emission values measured in the laboratory by the WLTP.
If official fuel consumption and CO2 emissions are already reported on the vehicle registration certificate and on the car brochure, why are the fuel consumption values reported on this website useful?
Over the last two decades, the real-world fuel consumption values of new passenger cars have become increasingly different from car manufacturers’ official specifications. The average deviation from official fuel consumption levels in 2001 was about 9%, but in 2017 it had reached an average value of 39%, without there being any change in the certification procedure during this time. Although the recent switch from the New European Driving Cycle (NEDC) to the Worldwide Harmonised Light Vehicles Test Procedure (WLTP) will likely reduce the gap between official and real-world fuel consumption and CO2 emissions values, there are indications that a substantial divergence could remain in the future.
Against this background, the MILE21 project aims to make realistic fuel consumption and emissions values for new and older car models available to consumers. To obtain these values, fuel consumption data provided directly by consumers through the MILE21 website will be considered, as well as other data sources.
Why does my fuel consumption differ from the value declared by the car manufacturer?
Despite the recent adoption of the Worldwide Harmonised Light Vehicles Test Procedure (WLTP), which may lead to more realistic fuel consumption values declared by manufacturers, real on-road values remain different from those derived from laboratory tests. In the real-world many different aspects can make cars consume more fuel than in the laboratory, including ambient temperature, traffic, driving style, air conditioning, and car loads.
How reliable and accurate is the data shown on this website?
Mile21 will compile data from several vehicle data sources. This data will include official data (e.g. engine specs and official fuel consumption values of each car model), fuel consumption data derived from statistical models, real-world emissions testing data, and on-road fuel consumption data shared by website users. Official data will rely on manufacturers’ product information and will be uploaded to the website unchanged.
On-road and laboratory measurements will be performed by LAT and TNO, who have extensive experience in the field and will, therefore, be able to ensure that tests are carried out following strict scientific protocol and using good engineering knowledge.
Fuel consumption data shared by users will be subject to plausibility checks at the time of input, but untruthful records cannot be avoided completely. However, while the experience of individual drivers might differ significantly, aggregate data from a larger group of drivers will provide a good indication of how a certain vehicle model performs in the real world.
How can I reduce fuel consumption and CO2 emissions by eco-driving?
Fuel consumption and CO2 emission are directly linked: saving 10% of fuel reduces CO2 emission by 10%. Using fuels with more bio-admixture like E10 instead of E5 will also reduce total greenhouse gas emissions, as the carbon that is contained in the ‘bio’ part of the fuel is from renewable sources instead of from fossil fuels.
In general, you can reduce your fuel consumption most effectively by avoiding unnecessary braking, as well as by avoiding high speeds on the highway, typically over 100 km/h. This is because most of the power that the engine has to deliver is needed to accelerate back to speed after a stop or to push the vehicle through the air, even in a very sleek vehicle. If you drive a lot in the city, your fuel consumption can decrease significantly if you anticipate by letting the car coast to traffic lights from 100 meters away or farther. The same applies to traffic jams. If you drive slower on the highway, the trip will obviously take a bit longer. In real-world circumstances, this difference is often negligible (a few minutes), unless very long distances are driven on the motorway. Note: keep it safe. Never create unsafe situations because of eco-driving.
Keeping a vehicle in a proper state will also help to avoid high fuel consumption: tyre pressure, parasitic braking (brake pads touching the brake disk while driving), wheel alignment (e.g., misalignment caused by small accidents), high unnecessary payload or roof racks (i.e., ski racks and stored snow chains in the summer) can all contribute to a higher fuel consumption.
How can MILE21 help me find out what the real-world fuel consumption of my car is? How can it help me make an informed purchase decision if I am planning to buy a car?
The MILE21 partners have developed models that predict real-world fuel consumption based on trends identified during on-road fuel consumption monitoring. The MILE21 project will expand and use these models to provide realistic fuel consumption data to users. The monitoring will be expanded using European-wide user feedback which will further improve the predicted fuel consumption values. When consumers consider purchasing a new vehicle, they can compare realistic fuel consumption values for the vehicles that are of interest.