New emissions tests come into force

Two new tests for measuring emissions from cars and vans came into force across the European Union at the start of September with the aim to introduce more realistic driving conditions and therefore more accurate results.

The previous testing regime, the laboratory-based New European Driving Cycle test (NEDC) originally designed in the 1980s, is replaced by a new test, the Worldwide Harmonised Light Vehicle Test Procedure (WLTP). This is intended to introduce more realistic testing conditions for measuring pollutant and CO2 emissions.

The WLTP applies to all types of new cars from September 1st this year and to all new car registrations from the same date next year. As a result, it should provide a more accurate basis for measuring a vehicle’s fuel consumption and emissions, and provide uniformity on an issue which has caused considerable controversy in recent years.

In addition to the WLTP, a new test to measure pollutant emissions on the road – known as the Real Driving Emissions test (RDE) – will also apply from September 1st, making Europe the only region in the world to implement such rigorous testing.

Under RDE, a tested car will be driven on public roads over a wide range of conditions using portable measuring equipment. RDE will complement WLTP to ensure that pollutant emission levels, measured during the laboratory test, are confirmed out on the road.

The transition to the WLTP will happen in phases and the new test will officially apply to new types of cars that are introduced to the market for the first time from this September.

Manufacturers may already start requesting WLTP approvals for all new car types from the September 1st introduction of the EU-wide legislation. The WLTP will then apply to all new car registrations from September next year.

The WLTP driving cycle is divided into four parts with different average speeds: low, medium, high and extra high.

Each part contains a variety of driving phases, such as stopping, acceleration and braking. For a certain car type, each powertrain configuration is tested with the WLTP for the car’s lightest (most economical) and heaviest (least economical) version.

The WLTP will introduce:

  • More realistic driving behaviour
  • A greater range of driving situations (urban, suburban, main road, motorway)
  • Longer test distances
  • More realistic ambient temperatures, closer to the European average
  • Higher average and maximum speeds
  • Higher average and maximum drive power
  • More dynamic and representative accelerations and decelerations
  • Shorter stops
  • Stricter car set-up and measurement conditions

Because of these improvements, the WLTP will provide a much more accurate basis for calculating a car’s fuel consumption and emissions. This will ensure that lab measurements better reflect the on-road performance of a car.

Even though WLTP will be more accurate, it will not cover all variations globally – and certainly not each individual driving style. There will therefore still be a difference between emissions measured in lab conditions and the real world, as driving behaviour, traffic and weather conditions will continue to differ from one country to another.

To help measure this, the complementary RDE will test a car on public roads and over a wide range of different conditions. Specific equipment installed on the vehicle will collect data to verify that legislative caps for pollutants, such as NOx, are not exceeded.

Conditions will include:

  • Low and high altitudes
  • Year-round temperatures
  • Additional vehicle payload
  • Up-and down-hill driving
  • Urban roads (low speed)
  • Rural roads (medium speed)
  • Motorways (high speed)

The RDE test will be implemented this September for all new types of cars and will apply for all registrations from September 2018. The test will mean that nearly all diesel vehicles will have to be fitted with selective catalytic reduction (SCR) systems and some lean-NOx systems as well.

This will mean additional costs for car manufacturers and smaller cars may not be able to accommodate the fitting of SCR equipment, while some potential owners may be deterred by the extra costs.

ACEA, the umbrella trade association representing the European automotive industry, has launched a new website to provide a greater insight into the various vehicle emissions tests.

The new Car Emissions Testing Facts website provides a fact-based overview on everything related to the testing of car emissions in Europe, including the UK.