Fuel consumption and emission tests and requirements are strictly prescribed by the EU, and the certification tests are carried or witnessed by independent type-approval authorities. The independent type-approval authorities carry out thousands of vehicle tests and certifications using scientific, comparable and repeatable tests.
Why do cars have to comply with CO2 emissions?
Vehicle manufacturers have delivered huge gains in fuel efficiency, reducing by more than a third the total consumption of their cars since the 1990s. Further improvements are ahead as the industry works towards minimising the environmental impact of the cars, vans, trucks and buses that keep society and the economy moving.
Before any new vehicle can be placed on the market, it has to comply with rules and regulations laid down by the European Union. Among many others, these include safety, weight and dimensions, lighting, tyres, braking requirements. Chief amongst the rules that new cars must meet are emissions and fuel efficiency requirements.
Fuel efficiency and emissions information is derived from a part of the type-approval process called the New European Driving Cycle (NEDC) test, which is a standardised procedure designed to compare different vehicles under the same conditions. Its aim is to represent car use, in a repeatable, consistent and measurable fashion. As such, the test is necessarily performed under laboratory conditions according to legal requirements, which are different to real life conditions.
The tests set out by the EU regulator are carried out by fully independent or nationally-authorised testing bodies, or are carried out with official oversight. Similarly, the objectives of the test are precise, and the rules governing what is allowed or not are very clearly defined. There are some small tolerances, as in any scientific tests, to account for the differences between vehicles and between the different independent type approval authorities’ testing capacities.
The test procedure builds a simulated picture of a vehicle’s environmental performance during a specifically defined task. The test, carried out on a dynamo, simulates a variety of different driving scenarios, not all of which will necessarily be experienced by each driver in the real world in such a repeatable and scientific way.
The nature of the test means that it is even possible to compare the fuel consumption and CO2 emissions of very different cars: the tests they complete are identical and carried out in the same manner and under the same conditions, providing consumers with clear comparability.
Making the results clear
The New European Driving Cycle’s purpose is to enable consumers to make a comparisons between vehicles. The actual real-world fuel-efficiency experienced by drivers varies widely as it depends on many external factors such as traffic conditions, terrain, driving behaviour, road type, vehicle load, etc. In real-world conditions, even if two different drivers drive the very same vehicle under the very same conditions, each will have a different consumption performance.
Drivers may not see the same figure as indicated because the New European Driving Cycle is a compound test that assesses the vehicle’s performance in a variety of simulated environments. The results are then adapted into the Urban, Extra-Urban and Combined Cycle figures, but most drivers do not do all of these types of journey in a single sitting.
While this might mean that many drivers exceed the quoted emissions figure, recent research shows that by driving carefully some drivers can in fact beat the NEDC figure by over 5%. The industry is an active participant in a number of eco-driving projects across Europe, and this kind of driver training is now a requirement of most driver’s licence courses for new learners.
Improving the test
Aware that the NEDC test could be improved, and in order to give consumers better information, the industry is actively involved in the discussions on a replacement for the NEDC called the Worldwide harmonized Light vehicles Test Procedures, (WLTP).