WLTP - Worldwide harmonized Light vehicles Test Procedure

1. What does WLTP stand for?

WLTP is the acronym for "Worldwide Harmonized Light-Duty Vehicles Test Procedure'. This is the test procedure in the EU for exhaust-emissions and fuel-consumption values for new vehicles. This test procedure has been valid for new type approvals for M and N1 category vehicles in the European Union from 1st September 2017 and all new vehicle registrations from 1st September 2018.

2. What does NEDC stand for?

NEDC is the acronym for 'New European Driving Cycle" and is the previously applicable test cycle for determining exhaust-emission and fuel-consumption values in the EU and some countries in the rest of the world.

3. What is the difference between the measurement methods?

Whereas with the old test, the test values were based on a synthetic driving profile, i.e. New European Driving Cycle (NEDC), the WLTP cycle (WLTC) is based on data collected world-wide during road use. It therefore permits a better representation of everyday driving profiles. The NEDC is based on two driving-profile phases: urban and extra-urban.

The combined CO2 and fuel-consumption values as well as the combined pollutant emissions are obtained based on these. The WLTP driving cycle is divided into four parts with different average speeds: low, medium, high and extra high. Each part comprises multiple driving, stationary, acceleration and braking phases. In addition to the driving profile, the measuring procedure has been adapted and the current vehicle technology has been adapted with the WLTP. The specifications, e.g. at what temperature the vehicle is to be tested or what tyre pressure has to be set are more strictly defined. The new test cycle and the new test procedure are characterised by the following:

- More realistic driving cycle
- Greater range of vehicle speeds/vehicle speed types (urban, extra-urban, motorway), providing the customer with specific fuel consumption data for each speed type within the WLTP test
- Longer test distance
- More realistic ambient temperatures closer to the European average (in addition to the 23 °C test, a 14 °C test will be introduced which reflects the average temperature of the EU)
- Higher average and maximum speeds
- More dynamic and representative acceleration and braking phases
- Shorter stationary period in relation to cycle duration
- Consideration of optional vehicle equipment: Specification of CO2 values and fuel consumptions for each individually configured vehicle, taking into account additional equipment (spoiler, sunroof, tow bar etc.)
- Limitation of measurement tolerances

The specification of best and worst-case values in the WLTP in the user information reflects the possible influence of the optional equipment. It is possible to determine a vehicle specific, equipment-dependent value by interpolating between the worst and best case specification values.

4. What are the advantages of WLTP?

Due to all these changes, the WLTP provides a more realistic basis for the determination of fuel consumption and emissions data for vehicles.

The WLTP test was developed with the objective of standardising the determination of pollutant and CO2 emissions as well as fuel consumption data through its use as a global test cycle. The "core" of the WLTP test is the same world-wide. However, the European Union and other regions will adapt it to their respective road traffic regulations and requirements. There are also numerous countries who will not be introducing the WLTP, for example the USA.

5. Will WLTP put an end to the discrepancy between the values measured in the laboratory and those achieved during road driving? What is the difference between WLTP & NEDC? What difference is there between the measurement methods?

The WLTP is expected to reflect the existing road conditions more realistically than the NEDC, but will not cover all the possible variations. Moreover, each individual driver will continue to have a very personal driving style: While one person accelerates more rapidly, drives faster into bends or brakes more abruptly, another drives more defensively. Furthermore, during real operation, the weather conditions (e.g. head wind/ tailwind, different ambient temperatures), use (e.g. full loading, trailer operation), ancillary loads (e.g. radio, air conditioning etc.), altitude, inclines and the route profiles (only short trips, only motorway etc.) are additional factors which significantly affect fuel consumption.

In light of the differences with regard to driving behaviour, traffic situation and weather conditions in the individual countries, which will continue to apply in the future, the deviations between the emissions measured under laboratory and real conditions will also persist. However, because a "true" emissions and fuel consumption value does not exist in practice, it is only possible to make direct comparisons of the emissions and fuel consumption of the various models of different automotive manufacturers using measured values obtained during standardised laboratory tests.

6. What values (WLTP) are measured on the roller test stand?

During the laboratory tests in the context of the European type approval of passenger vehicles, the CO2 emissions, which bear a direct relation to fuel consumption, pollutant emissions and the energy-consumption values of alternative drives, including electrically driven vehicles are measured.

7. What is type approval?

Laboratory tests play a decisive role in the process of introducing a motor vehicle onto the EU market. Before vehicles are launched on the market, they are subjected to certain tests by a technical service in accordance with EU law. If all the registration-relevant requirements are met, a national authority issues the manufacturer an EU type approval form authorising the sale of that particular vehicle type in the EU. Every vehicle produced for the EU market is provided with a Certificate of Conformity (so-called CoC document), which, in addition to other information, includes the CO2 emission values from the laboratory test. On the basis of this document, registration of the vehicle is possible everywhere in Europe.

8. How can the motorist know what CO2 emissions the vehicle produces?

To enable motorists to make a well-founded purchase decision based on fuel consumption, car dealers and manufacturers provide the consumer with relevant information, including an indication of the CO2 emissions and fuel consumption for a passenger car, which is displayed on or near all new vehicles in the showrooms. The design of these labels is specified at a national level (and therefore differs from country to country). However, they all include the CO2 values from the standardised laboratory tests, which are also contained in the Certificate of Conformity (CoC document).

9. What is the connection between CO2 emissions and taxation?

In most EU member states, the amount of the registration tax (one-off) and/or the vehicle tax (annual) depends on the CO2 emissions of the vehicle. This taxation is based on the CO2 values obtained during the laboratory testing contained in the Certificate of Conformity (CoC document). In the UK, NEDC CO2 values will continue to be used for taxation purposes until April 2020.

Re: WLTP - Worldwide harmonized Light vehicles Test Procedu

WLTP - FAQ


1. When will the changes enter into force?

The WLTP legislative package has been fully valid since 27.07.2017. This means that from 01.09.2017, new vehicle types will be type-approved in accordance with WLTP. From 01.09.2018, all new vehicles (new registrations) will be type-approved according to WLTP. There are legal provisions in place for end-of-series vehicles, which make it possible to stock a limited number of vehicles approved according to the old procedure and to sell these by 31.08.2019.

2. What is the actual fuel consumption of my vehicle (not NEDC or WLTP)?

The actual individual fuel consumption depends on a wide variety of factors (i.e. ambient temperature, traffic situation, driving style, inflation pressure, altitude, inclines, head wind/ tailwind, etc.). The WLTP should however, deliver more realistic CO2 emissions and fuel consumption values.

3. According to the WLTP method, the results of the test will be higher. Does this mean that my fuel consumption has increased?

In practice and with otherwise unmodified technology, the actual fuel consumption will not change. For one and the same vehicle, the WLTP test will result in higher CO2 and fuel-consumption values than the NEDC test for the simple reason that the driving profiles and the measurement conditions (maximum speeds, dynamics, etc.) differ between the two test cycles. This means that the WLTP is more representative of today's road traffic conditions than the NEDC. The CO2 value according to WLTP therefore corresponds more closely to customer expectations owing to the changed measurement methods.

4. Will the WLTP test affect the cost of my vehicle tax?

Vehicles tested under WLTP are likely to have different CO2 values compared to current NEDC. Until April 2020, a NEDC 2.0 value generated from the WLTP test cycle using a correlation will be used for the purposes of taxation in the UK. From April 2020, the WLTP CO2 figure will be used for taxation purposes.

5. How can it be that a passenger car suddenly has two different CO2 values?

Before the start of the transition period from NEDC to WLTP, which begins from 01.09.2017, only the CO2 values measured according to the NEDC test continue to apply for all registered vehicles.

When a new car is type approved after 01.09.2017, the official Certificate of Conformity for the vehicle contains both the CO2 emissions values according to the new laboratory test (WLTP) as well as the NEDC values simulated using the correlation tool or actually measured using the updated NEDC test.

Accordingly, after 01.09.2017, when the change from the old NEDC test to WLTP is complete, you may find different CO2 values in the CoC document for your vehicle. From 01.09.2018, both the NEDC as well as the WLTP CO2 values must be indicated for all new vehicles. From 2021, it is expected that only the WLTP value will be indicated in the CoC.

6. What is the difference between NEDC 1.0 and NEDC 2.0?

NEDC 1.0 values are values, which were determined through the previous NEDC test methods. With NEDC 2.0 vehicles are already typed with WLTP standard; the insofar indicated NEDC values are values which are derived (correlated) from WLTP.

7. Why does Porsche not already indicate fuel consumption according to WLTP today? Why has Porsche not indicated fuel consumption according to both standards in the past?

Government legislation requires all manufacturers to currently publish fuel consumption based on NEDC. We only publish officially approved CO2 and fuel consumption information. Because we do not yet currently have any WLTP-homologated models on the market, we are as yet unable to provide any values. Because the laws on customer communications have not yet been adapted at the start date for WLTP (01.09.2017), the NEDC remains binding.

8. When will I be able to purchase Porsche vehicles that comply with the Euro 6c standard?

The legislation stipulates that registrations for all new vehicles from 01.09.2018 are only possible with at least Euro 6c.

9. Why is Porsche not already manufacturing vehicles that meet the already familiar new standards (e.g. Euro 6c) today?

In the context of the model cycles, we ensure that all of our vehicles comply with the standards and regulations required by the legislators over the entire duration of their sale and delivery. Unfortunately, it cannot be ensured that future standards be taken into account over this entire period.

10. Euro 6d-Temp applies since autumn 2017. Does my vehicle meet this emission standard?

The Euro 6d-Temp standard will be valid for new type-approved vehicles from 01.09.2017. This means that all the new models presented to the legislators for type approval must comply with this emission standard. For existing models and those currently for sale, the emission standard Euro 6c will only become compulsory for registration from 01.09.2018.

Type approvals/registrations which have already been completed remain valid under the current law, even if new standards come into force.

11. I would like confirmation from Porsche that I will not be disadvantaged if my vehicle does not comply with the new standards. / Do I have to have my old Porsche re-tested?

The new Eu6c standards do not apply retrospectively, so the provisions and requirements valid at the time of registration apply, and vehicles already registered within the UK will not require re-testing. We cannot confirm or comment on possible changes in future UK legislation that may affect vehicles that only meet older emissions standards.

12. Can I retrofit my vehicle from Euro 5 to Euro 6?

No, it is not possible to retrofit a Porsche from Euro 5 to Euro 6 whilst maintaining our quality and safety standards.

13. Surely Porsche should be making every effort to ensure that I can continue to use my Euro 5 vehicle without restriction.

Porsche follows the political and media debate surrounding the identification of low-emissions vehicles very closely – including all the potential consequences for today's vehicle fleet. Essentially, we welcome and support considerations that serve for the benefit and protection of citizens. Accordingly, all the current models comply with the Euro 6 standards and therefore meet the latest current requirements. Furthermore, Porsche supports the extensive measures of the Volkswagen Group, which were agreed during the "National Diesel Forum', aimed at further improving the air quality in cities.

14. What is a petrol particle filter? (PPF)

A petrol particle filter is a particle filter for petrol engines. It enables the reduction of fine soot particulate matter emissions.

15. Does my vehicle have a particle filter?

Our vehicles with petrol engines do not currently feature particle filters. Our vehicles with diesel engines from EU4+ are all equipped with a diesel particle filter.

16. Why does my vehicle require a PPF?

To date, particle filters are only familiar from diesel engines, however, direct injection technology, which is increasingly being used in petrol engines, increases particulate matter emissions in comparison with intake manifold injection. Because the fuel is injected directly into the combustion chamber, individual droplets can be deposited on the cylinder walls, pistons or valves, where they partly combust incompletely and remain as minute soot particles.[*]

[*] t-online.de report: VW bringt Partikelfilter für Benzinmotoren (VW introduces particle filters for petrol engines) 3/8/2016, 4:42 p.m. | Hanne Schweitzer, SP-X

17. What effects does the PPF have on the service life of the vehicle, particularly on the engine? How maintenance-intensive is the PPF?

As is the case with the particle filters already used on diesel vehicles, we do not anticipate any impairment to the service life of petrol vehicles featuring a particle filter.

No maintenance is required or envisaged. There is no effect on the service life of the engine because its thermodynamic and mechanical limits are not exceeded. As a rule, regeneration of the filter is passive, so that the driver is unaware of it taking place. Only in the event of lengthy vehicle operation at very low engine loads in conjunction with short distances and frequent cold starting, are the operating parameters of the engine configured to allow passive regeneration to take place (e.g. higher shifting speeds).

18. When will the particle filter become available for all Porsche models (petrol engines)? Is a retrofit available?

Please appreciate that we are unable to make any specific statements on a possible retrofit of already registered vehicles with regard to model updates at this point in time. You may however rest assured that Porsche is closely monitoring the rapidly changing technology and legislation in this area and will respond accordingly.

19. What does the change/homologation according to WLTP have to do with the PPF?

In essence, nothing. The petrol particulate filter is requied to comply with RDE (Real Driving Emissions) limit value requirements.

20. What is RDE?

RDE stands for Real Driving Emissions, which comes into force alongside the WLTP. RDE involves monitoring of vehicle emissions during real drive cycles using Portable Emissions Measuring System (PEMS). This has been made possible through recent technological advances in emissions measuring equipment. To comply with RDE, vehicles will need to stay within certain emissions limits during tests which will be carried out in real-world conditions.

Fuel consumption figures and emissions data: countdown to WLTP.

While we can definitely say that fuel consumption figures never stop being key data for fleet managers, the whole transport and vehicle manufacturing sectors are paying particularly close attention to the current news concerning the abolition of the NEDC (New European Driving Cycle) emissions and fuel economy testing regime in favour of the new WLTP (Worldwide harmonized Light vehicles Test Procedure) regime.

By the deadline of September 1st, 2018, vehicle manufacturers will have to make sure all new cars and lighter vans have been tested under the new protocol, which should"”at least this is the idea"”provide the relevant consumers and fleet operators with more representative fuel consumption and CO2 emissions figures.


The WLTP has been developed within the United Nations Economic Commission for Europe (UNECE) supported by the European Commission to provide more realistic test conditions, in an attempt to better reflect what drivers experience in the real world. The test will eventually be combined with the RDE, the new on-road 'Real Driving Emissions' test, whose 'Step 1' has been active since September 2017. In RDE tests, a vehicle with specific equipment installed is driven on public roads and over a wide range of different conditions collecting data to verify that legislative caps for pollutants such as NOx are not exceeded.

While there seems to be confusion about the different types of fuel consumption and emissions testing, the fleet sector is already hypothesising about the implications of the September 1st deadline: will there be changes in the benefit-in-kind taxes? Will there be confusion due to the possible coexistence of two identical vehicles having different fuel economy figures because they have been approved over different drive cycles? And will vehicle manufacturers be forced to offer heavy discounts on cars that don't meet standards, at least within the grace period that some countries already offered after the 1st of September?

In this current state of confusion, a few days ago the Swedish manufacturer Volvo (one of the most typical company car brands) became the first to have every model across their car range comply with the new WLTP rules. This includes all petrol and diesel-powered models, plus the collection of hybrid vehicles offered by the Swedish brand. Quite a significant step: as from September 2018 all new cars will have to be certified according to the WLTP test and not NEDC, and cars that aren't WLTP-compliant by the September deadline will be barred from sale.

While both fleets and motorists are still experiencing some confusion and automakers start getting their heads around WLTP, others are objecting that even with a test that more closely mimics real driving conditions with supposedly more realistic data there may still be a gap between the test and reality. If you really wish to be in possession of real fuel consumption figures, only technology measuring real consumption data can provide a realistic answer.

Earlier in the summer, Porsche was the latest manufacturer to suspend model production due to the new Worldwide Harmonised Light-Vehicle Test Procedure (WLTP).

The company has said that it will temporarily limit the number of models it sells in Europe, as it readies its fleet for the new test procedures, which include a real-world driving emissions (RDE) component. Waiting times for the Cayenne SUV and Panamera could be until at least March 2019. The 911 model won't be available until autumn, after the new factory upgrades are complete.

A quote from the company's website configurator, reported in the Frankfurter Allgemeine Zeitung (FAZ) publication, said: 'Due to a pending model revision, the model you have selected is currently not available as a freely configurable new car. Nevertheless, we would like to give you the opportunity to continue to look at the model in the Car Configurator. If you are interested in configurable new cars, available existing vehicles and young used vehicles, please contact your Porsche Centre.'

Porsche officially announced that the introduction of the new exhaust emission legislation necessitated a conversion of the model range to include a petrol particulate filter (PPF) and a new type approval submission by 1 September 2018 at the latest.

WLTP was introduced for new vehicle models in September last year and will be applied to every vehicle base from September 2018. This takes into account the optional extras included across every vehicle specification and features tests in real driving conditions alongside laboratory results.

In May, Peugeot announced that production of the 308 GTI would be suspended for around four months, to allow for petrol particulate filters to be engineered into vehicles, while BMW has also halted the manufacture of vehicles to ensure they comply with the RDE portion of the test.

The management of Volkswagen (VW) is also considering a reduction of holidays at its plants. 'The changeover to the new WLTP test procedure will mean that Volkswagen Passenger Cars will be able to make adjustments in production in the second half of the year,' a brand spokesperson told Automobilwoche.

Both Volkswagen (VW) and BMW are looking to reduce their model versions as the manufacturers seek to move finances around in the wake of WLTP and the need for the development of new technologies.

Manufacturers that need to fit petrol particulate filters to reduce particulate matter emissions for the RDE need time to source supply and re-engineer their vehicles to fit the extra exhaust section, while also installing new software into the ECU to get it working. Much like a diesel particulate filter (DPF), the PPF catches fine particles from the exhaust system and burns them off harmlessly through a process called 'regeneration'.

Unlike diesel engines, which regenerate at temperature, regeneration in a PPF takes place under deceleration. Oxygen is pumped through the engine and filter passively, without heat.

Volkswagen deliveries halted by WLTP emissions certification

VW has confirmed that only half of its models have gained type approval ahead of 1 September deadline

Volkswagen says just half of its existing models have gained type approval under the latest emission regulations, following delays in a new certification process.

From 1 September all new cars sold within the European Union are obliged to fulfil tough new regulations as part of the so-called Worldwide Harmonized Light Vehicle Test Procedure (WLTP) developed to provide a more realistic measure of fuel consumption and emissions.


However, Volkswagen's head of sales and marketing in Germany, Thomas Zahn, has confirmed the company has only achieved type approval for seven of the 14 model lines sold in Europe.

'The new tests are more cumbersome and take two to three times longer than in the past. Even limited edition models need to be tested separately," Zahn said in a conference call with journalists this week, adding, 'The coming months will be challenging for us."

Significantly, Volkswagen's best selling model, the Golf, is among the models yet to have gained total clearance. The volume-selling variants are expected to be certified in the next two weeks, with the brand's test bench running 24hrs a day to clear the certification process.

The delay has left Volkswagen with growing customer unrest as delivery times on popular models are forced to be extended, with some Golf variants delayed by as much as six months, according to German dealer sources, who described the situation as 'disastrous".

Zahn said he expects the full Golf range to gain certification clearance by the end of September. Even so, some customers are already being quoted delivery times into 2019. A Volkswagen UK spokesperson has confirmed that the average lead time for most Golf variants here is around 14 to 15 weeks, up from 6 to 10 weeks before WLTP was introduced.

In anticipation of the delay in deliveries due to the WLTP certification, Volkswagen has begun stockpiling new cars produced at factories around Europe. 80% of those cars are already sold, however.

The German car maker recently revealed it had rented ground space at Berlin's new international airport, which has yet to open, to accommodate thousands of newly produced cars with the intent to begin delivery as soon as they have been granted type approval by authorities.

BMW has increased the CO2 outputs and lowered the MPG of its entire range following retesting with the new Worldwide Harmonised Light Vehicles Test Procedure (WLTP).

The largest increase in CO2 was seen with the BMW 520d SE Automatic, which is now rated at 119g/km, a growth of 17g/km – or a 14% jump compared with the previous New European Driving Cycle (NEDC) test results.

Every model has also seen a reduction in economy, with the aforementioned 520d variant falling from 72.4mpg to 62.7mpg. The figure changes to this model will enforce a 3% rise in tax for company car drivers.

Even cars at the entry-level have been affected, with the 116d SE rising from 94g/km of CO2 and 78.5mpg to 111g/km and 67.3mpg respectively. The 116d SE Automatic now produces 116g/km and 64.2mpg, up from 99g/km and 74.3mpg.

BMW said that the number adjustments are attributed to the WLTP tests, which are widely regarded as being considerably more stringent than the outgoing NEDC process due to the incorporation of more accurate real-world driving scenarios.

How are plug-in hybrids and electric cars measured?

In order to obtain type approval, electrified vehicles will also have to be tested according to the new WLTP rules in Europe. Just as the fuel consumption figures for vehicles with internal combustion engines will change with the WLTP's roll-out, the same will apply to the range specifications of pure electric cars and plug-in hybrid vehicles. The range specifications are more representative with the WLTP. The electrical range that is actually usable for customers will not change.

For purely battery operated electric vehicles, this means that the higher average speed of the new test cycle leads to a higher energy consumption. This energy is stated, however, not in liters, but in kilowatt-hours (kWh) per 100 kilometers. The measurement is carried out as prescribed in the previous fuel consumption measurement specification: the battery must be fully charged at the start of test bench test. Immediately after testing, test engineers reconnect the vehicle to a charger. The cable is equipped with an electricity meter. This meter measures the total amount of current, which has the advantage that the battery's energy losses during charging are detected as well. The resulting value is divided by the range determined in test bench testing.

Roll-out of the WLTP signifies a major change for plug-in hybrid vehicles, which have both an electric drive and a combustion engine and can be externally recharged. These vehicles complete the test several times. They start up with a full battery. The cycle is repeated until the battery is empty. The combustion engine operates for a longer time each cycle. Emissions are measured with each cycle. This is followed by a measurement with an empty battery in which the drive energy originates solely from the combustion engine and regenerative braking. This multi-stage measurement can not only be used to determine fuel consumption and CO2 emissions more precisely, but the electrical range and total range as well. The CO2 value to be determined is then calculated as the ratio of the electrical range to the total range. At the same time, a so-called 'utility factor" (UF) is introduced.

The UF represents the proportion of vehicle distance traveled electrically. In the case of pure electric vehicles, a UF of 100% applies. In the case of traditional internal combustion engines, the UF is 0%. In the case of plug-in hybrid vehicles, the UF increases with their electrical range. Lawmakers can use the UF to evaluate a vehicle's ability to drive without emissions. The higher the electrical range, the lower the CO2 emissions.

This is quite close to real-life conditions since the driver of a plug-in hybrid will have to refuel less often when he or she has sufficient current available, e.g. to drive typical commutes purely electrically. In practice, the actual consumption behavior of a car with plug-in hybrid drive will vary widely from one user to another. In the case of long-distance trips, the electrical distance traveled is negligible and the consumption will be on a par with the traditional combustion engine. On the other hand, many short-distance trips and commutes can be covered almost entirely electrically, with actual fuel consumption close to 0 l/100 km.