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WLTP

The Worldwide Harmonised Light vehicles Test Procedure (WLTP) has been created to define a brand new global harmonised standard for determining levels of pollutants and emissions, fuel consumption, and electrical range in light-duty vehicles.

WLTP will replace the previous fuel economy testing, known as the New European Driving Cycle (NEDC), which was introduced back in 1992.  Since September 2017, all new models introduced to the market for the first time have been tested to WLTP.  All cars sold from September 2018 will be tested to WLTP.  This new laboratory testing will also be supplemented by an emissions test that measures pollutants directly on the road to produce Real Driving Emissions (RDE).

The new WLTP test procedures will enable consumers to have more accurate fuel consumption and CO2 emissions of their vehicles.

Citroen-WLTP

FROM NEDC TO WLTP

The new WLTP test conditions are based on an approximation of real-world driving conditions, offering clearer and more realistic values. The WLTP enforces much stricter and redefined test conditions and introduces higher speed testing together with a substantially longer test duration (now 30 minutes instead of 20). 

In order to obtain more accurate CO2 emissions, the new test procedure includes both standard equipment and all optional equipment of the vehicle. This produces fuel consumption and CO2 emission values according to aerodynamics, weight and rolling resistance.

This means that in the case of a specific vehicle configuration, an individual specific value will be indicated rather than a more generic one, as was the case previously.

Initially, the values measured within the WLTP will be a recalculation back to the  NEDC values - this is because the EU Commission has developed a correlation technique for this purpose, which is intended to help the transition from NEDC to WLTP. The duration of this phase will depend on the respective national legislation and will thus vary from market to market.

From September 2018 all manufacturers will be obliged to test in accordance with WLTP for vehicles sold in the EU as well as in Switzerland, Turkey, Norway, Liechtenstein, Israel and Ireland.

MAIN DIFFERENCES BETWEEN THE TWO TEST PROCEDURES

NEDC WLTP
Test cycle Single test cycle Dynamic cycle more representative of real driving
Cycle time 20 minutes 30 minutes
Cycle distance 11 kilometre 23.25 kilometre
Driving phases 2 phases, 66% urban and 34% non-urban driving 4 more dynamic phases, 52% urban and 48% non urban
Average speed 34 kilometre per hour 46.5 kilometre per hour
Maximum speed 120 kilometre per hour 131 kilometre per hour
Influence of optional equipment Impact on CO2 and fuel performance not considered under NEDC Additional features (which can differ per car) are taken into account
Gear shifts Vehicles have fixed gear shift points Different gear shift points for each vehicle
Test temperatures Measurements at 20-30°C Measurements at 23°C, CO2 values corrected to 14°C

ON-ROAD REAL DRIVING EMISSIONS

In addition to the WLTP, RDE will also be compulsory for all vehicle manufacturers in the EU as well as in Switzerland, Turkey, Norway, Liechtenstein, Israel and Ireland from September 2018.

In these RDE tests, a car is equipt with a Portable Emissions Measurement System (PEMS) and is driven on public roads. The PEMS collects data to verify that the legislative caps for pollutants are not exceeded and determines the average emission values that can be realistically expected during everyday driving (NOx, PN).

The collected data is then analysed to verify that the driving conditions fulfil RDE requirements and that emissions are within acceptable limits.
Essais PEMS 2

What is WLTP?

Citroen-C4-Cactus-Hatch

 

WLTP is an abbreviation for 'Worldwide Harmonised Light Vehicles Test Procedure. 

It's a new test procedure that gives a more realistic overview of vehicle fuel consumption and CO2 emissions that will be legally binding for all vehicles as of September 2018. WLTP will replace step-by-step the previously applicable New European Driving Cycle (NEDC) testing procedure.

FAQs

What is a WLTP driving cycle?

What does WLTP mean for me?

What is RDE?

What is EU6?

WHAT IS SELECTIVE CATALYTIC REDUCTION?

What is a particle filter?

What is the WLTP driving cycle?

A vehicle’s consumption and emissions always ultimately depends on individual driving style, which has resulted in driving data being compiled for WLTP from all around the world. This data has been used to define four representative phases with different average speeds: Low, Medium, High and Extra High. 

Within each of these phases, there are different intensities of braking, acceleration and periods where the vehicle is at a standstill  in order to reflect typical situations in everyday  motoring. The combination of these phases then results in what is known as 'the driving cycle.'

Fuel consumption values will be presented for four different driving conditions with an overall combined figure for petrol, diesel, hybrid and plug in hybrid cars. 

What does WLTP mean for me?

The introduction of the WLTP will mean that the fuel consumption and CO2 emissions indicated in car specification guides will more closely reflect those in real-world driving. 

Because the WLTP takes in to account individual optional equipment in your vehicle (such as winter tyres or glass roof), this will additionally lead to even more realistic values as they are based on the configuration of your personal vehicle.

More realistic values however may also naturally result in higher consumption and CO2 values for vehicles with combustion engines and, of course a lower electric range for electric vehicles (including plug-in hybrids). This could also mean your vehicle may be subject to a higher rate of road tax (VED). However, cars approved under WLTP will continue to be taxed against the NEDC CO2 emissions value, so there is no change to the CO2 based taxation systems in the short term.  This includes vehicle tax (VED) and company car tax (BIK). It is not expected that any structural change will be made before 2019.

 

What is RDE?

RDE stands for 'Real Driving Emissions.' This is a new procedure for measuring pollutants such as nitrogen oxides (NOx) and diesel particulate matter.

The most significant aspect of RDE, as the name suggests, is that measurement takes place on the road under realistic driving conditions and not in the laboratory. A clever device known as a 'Portable Emissions Measurement System' (PEMS) is attached to the exhaust of the test vehicle for these tests.

 

What is EURO 6/EU6?

Euro 6 is the name of the current exhaust emission standard for pollutants. It defines lower maximum values for particulate matter and nitrogen oxide emissions than the previous Euro 5 standards.

From September 2018*, the EU6c emission standard will become compulsory, and in comparison to EU6b it specifies even lower limits for the content of particulate matter in petrol engine vehicles. The same threshold limit values apply for diesel engine vehicles within the cycle for both EU6b and EU6c.

EU6d-TEMP will be introduced from September 2019* and EU6d from January 2021*, which will once again slightly reduce the threshold limit values for the number of particles and nitrogen oxides in line with RDE.

*Applies to new vehicles. New vehicle types will each be subject to the new exhaust emission standards one year earlier.

What does selective catalytic reduction mean?

In order to further reduce the exhaust emission values of a vehicle, liquid ammonia - called AdBlue® - is fed into diesel engines' exhaust systems. Selective Catalytic Reduction (SCR) with AdBlue® reduces up to 90% of the nitrogen oxides. What remains is water vapour, nitrogen and CO2

What is a particle filter?

A particle filter reduces the particulate matter present in diesel engines and petrol engines.

 

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